Links

Developer links

gamedev is the premier game development site on the internet.
Whole Tomato Software produce the excellent Visual Assist line of products. If you use Microsoft Visual Studio, then you need VisualAssist. I'm telling you... you need it. It's not optional!
Wotsit's has information on just about every file format you can think of.
Any Win32 programmer should read Raymond Chen's blog "The Old New Thing" religiously. Lots of interesting stuff on Win32 development, including important information on what not to do (and even more importantly: why not to do it that way).
Other stuff not to do, be it as a coder or just in general in the IT industry, is presented in a humourous way at The Daily WTF.
Programmers' Heaven is a positively a huge site containing thousands of links to other programming resources.
RageStorm is being run by an Israeli team, which are friends of mine. You'll find some good tutorials on their site as well as some code snippets for Win32/DOS/ASM, games and some other resources.
flipCode was my favourite game development site. There used to be an image of the day, a lot of articles and tutorials and some good message boards. Unfortunately, the site has deteriorated over the past two years and has now been shut down. R.I.P. flipCode.

Stefan Thoolen is a very good friend of mine, former co-worker and an excellent programmer. His site (under construction) has cool stuff on his astronomy hobby as well as some Visual Basic projects.
Folkert van Heusden is one of the smartest people I know. He has lots of interesting pet projects and did some great tools for *nix, Windows and other platforms.
Avery Lee has made VirtualDub, my video editing software of choice. Not only did Avery create this excellent program, he also made it available for free!
Al Lowe is the creator of the infamous Leisure Suit Larry. Al shares some of his great sense of humour with us on his website. While you're there, sign up for the CyberJoke3000 mailing list. It cracks me up every day.
Wil Wheaton played Wesley Crusher on Star Trek: The Next Generation. Although some people weren't too fond of Wesley, there's no arguing that the actor is a cool guy. Check out his website to know what I mean.

PC Game Programmer's Encyclopedia is a collection of text files dealing with just about every aspect of game programming for DOS. The follow-up, the Win95 Games Programmer's Encyclopedia has never been (and never will be) completed, but there are still some pretty good articles in it.
SWAG archives are a compilation of a lot of Pascal source code conveniently categorized. Hasn't been updated in over 6 years, but if you do Pascal programming, you'll find some gems here.