Pow! is a free little program from AnalogX that kills those pop-up advertising windows that keep annoying you every time you visit your favourite web site. It doesn't identify and clobber pop-ups you've never encountered before (besides, sometimes pop-ups are used for legitimate content), but for adverts you've seen already and added to its list, it's very effective. (AnalogX has a bunch of other handy programs as well, such as Cookiewall, for monitoring what information web sites are storing on your computer.)
SocketWatch is a shareware utility that makes up for the poor time-keeping of so many computers (such as ones with aging batteries), especially when they're "off". Put it in your startup folder, and whenever you connect to the internet, it will contact one of the dozens of trusted timeservers it knows on the net and synchronise your PC's clock with it, so you can finally trust that clock in the lower-right corner of your Windows 95/98/ME/NT/2K system. (There are several other such utilities out there; this is the one I use.)
LitePC is a family of programs that began in an effort to speed up Windows 98, by disabling and/or removing the then-new "features" that slowed it down. Among other things, it demonstrated the lie that Microsoft's web browser was an integral and critical part of the operating system, because 98Lite (the original program of this line) allowed users to remove Internet Explorer and replace it with the quicker Win95 Explorer. It has since evolved to make it possible to disable (and re-enable) a wide variety of speed-robbing, and security-compromising features in Windows 98/98SE/ME. It's offered in a basic edition for free and a more powerful and flexible edition for a small charge. LitePC for Windows 2K/XP (which pose a whole new set of challenging opportunities to speed things up) is in the works.
For a while now, Windows has come with the ability to share a printer among several computers on a network. The problem is that the main computer needs to be on for the others to print, and it slows down whenever they do. The solution is a separate print server. Various commercial units will do the job, but a free modular software package (based on Linux) can get an "obsolete" computer you may already own to do the same thing. A 486, 8MB RAM, 1.44MB diskette drive, and an old ethernet card are all you need. It doesn't use a (noisy, power-sucking) hard drive, and no monitor or keyboard is required to run it. It's fairly easy to put together using Windows-based tools. Advanced hackers can configure it to accept print jobs from anywhere on the internet.
Another feature bundled into Windows is the ability to share an internet connection with other users on a local network, and a built-in "firewall" to keep your computer safe when it's on the net. Both of these features have serious flaws. The internet-sharing has the same problems as sharing a printer, described above. The problem with the firewall that it's only as sound as the operating system it runs on, and WinXP still ain't that sound. Coyote Linux solves both problems at once. You don't need to know anything about Linux to get it up and running. All it requires is a "useless" old PC (486 with 12MB RAM recommended, but even a 386sx can work), a 1.44MB diskette, and two old 10Mbps network cards (one to connect to your cable modem or DSL router, the other to connect to your computer or local hub). It can also be configured to use a dial-up connection. No hard drive, monitor, etc. is needed. Intermediate hackers can customise Coyote's filters to let them run a web/mail server on the same IP address(es) they use for web browsing, while still maintaining state-of-the-art security. Much cheaper than buying a custom-designed firewall device, and nearly as good. (The developer of Coyote also sells an inexpensive software package called Wolverine, which can turn an old Pentium into a commercial-grade firewall/VPN access point, comparable to a Gnat Box or Cisco PIX.) Another easy-to-configure firewall/connection-sharing option with similar hardware requirements, is ClosedBSD, which is based on the FreeBSD OS.
I've learned the hard way that the only way to keep your computer truly secure on the internet is to have a separate machine standing between it and the rest of the world, acting as a dedicated firewall. But if there's some reason you can't do that (such as not having such a machine available to run Coyote Linux), then you need to lock down your PC as best as you can. Windows XP's "firewall" tries to block access, but when (not "if") it fails, it doesn't detect and warn you about suspicious activity actually happening on your computer. ZoneAlarm does, and is also better at protecting you in the first place. (If you're running an older version of Windows on the net, GO NOW to ZoneAlarm's download page before you get cracked!) The basic version is free for personal use, and the "pro" version (which adds some protection from malicious e-mail and web nasties) is worth the price. Other similar products to consider: BlackIce Defender, Norton Personal Firewall, Sygate Personal Firewall for Windows.
For Mac OS, check out Intego NetBarrier or
Norton Personal Firewall.
A must-have item in this day and age - at least for techie types who need shell or command-line access to remote systems - is a secure replacement for telnet, and Windows doesn't include one. Unix-like systems and other shell-based hosts are great because you can access them from any machine in the world that has a TCP/IP connection... but without encryption, anyone can listen in on your entire session, including your password. SSH (Secure SHell) is an encrypted replacement, with servers available on most modern shell-capable hosts, but Windows only includes a telnet client. PuTTY is a free open-source terminal emulator for Windows (and RiscOS) that handles SSH. Mac OS users should take a look at the free open-source MacSSH.
Mac computers have been able to read disks from PCs for quite a while now, but Windows still can't read Mac-format disks (which is just how Microsoft wants it, because it makes Macs seem more "incompatible"). DataViz's MacOpener effectively solves that problem, and it works with floppies, Zip disks, CD-ROMs, etc. You can even create Mac-format disks to give to Mac users. It won't let you run Mac software (which is a much huger problem to solve), but it's great for sharing documents from cross-platform programs like Freehand or Photoshop. Conversions Plus adds the ability to convert documents from one program's format to another (e.g. AppleWorks/Mac to WordPerfect/Win). Media4's MacDrive and Acute Systems' TransMac are other good solutions to this problem. HFVExplorer isn't as polished, but it's free.
TransferPro has a version to read Mac disks on Unix-like systems.
Microsoft apparently doesn't believe that people should have easy access to file transfer protocol (except maybe to download files from a web site), so they don't even provide a user-friendly tool to use it. Ipswitch's ever-popular WS_FTP is one of the best. Whether you prefer the "classic" two-pane view of transferring files between your machine and another, or the more "modern" Explorer-style view that makes both sites look like local folders, it's easy to use, and increasingly powerful. You can use it to find files out on the net, automatically synchronise two sites, connect to multiple sites at once, schedule transfers, etc. WS_FTP Server is good for running on Windows NT/2K/XP, particularly to take advantage of the client's encryption capability.
The more expensive "professional" version of Windows XP includes a feature that lets you (or a support techie) take control of your computer from another WinXP machine, over a network. Which is nice as far as it goes, but Virtual Network Computing, a free open-source tool from AT&T's UK research lab, will accomplish that going from just about any operating system to another. As long as you have the right password, VNC effectively connects the keyboard, mouse, and monitor in front of you to another machine running VNC anywhere else in the world. For example, you could control your Linux computer at the office using the Java-enabled web browser on your iMac at home.
djbdns is a set of Domain Name System tools written by D.J. Bernstein, one of the internet's more prominent and uncompromising (or "loud-mouthed and arrogant") security experts. It's a replacement for BIND (Berkeley Internet Name Daemon), the software used by most sites to translate domain names to ip addresses and back. Although it works surprisingly well, DNS is one of the less elegant systems to evolve on the internet, and BIND - although improved in version 9.x - is a notoriously vulnerable and complicated implementation of it. The system itself may be beyond fixing, but djbdns addresses many of the shortcomings of BIND in particular. It's modular in design - separating the actual data server (tinydns) from the proxy software that answers user queries (dnscache) - and it's coded from the ground up for security. There's an unclaimed cash reward to anyone who can break it. It's free software (but not open-source, which is part of why it's not more widely distributed and deployed) for Unix-like systems.Despite its imperfections, BIND on Unix is still better than the DNS integrated into Windows Server. For that matter, I'd rather run BIND on Windows (as many Microsoft-dependent shops do) than Microsoft's proprietary approximation of the standard, mostly because any bugs discovered in BIND usually have fixes available promptly, and with Microsoft you never know when/if they'll fix them, or what they'll charge for the "ugprade".
Netware,
DOS