Some of the computing sites I've found useful

Web publishing, graphics design and the like

• Philip and Alex's Guide to Web Publishing - there's a whole site behind this link, with the best-written information about writing for the Web that I've ever seen. Philip Greenspan is also a startlingly good photographer.
• Nielsen Norman Group, useit.com, Ask Tog and Cooper Design Resources - collections of interesting articles about how to build user interfaces. Widget of the Week is something similar.

Specialist news sources

• The Register - an irreverent but very well-informed look at the computer industry.
• Anandtech, Firing Squad and Sharky Extreme - three strangely-named sites with very good (though extremely biased towards the game-player in the last two cases) reviews of the most recent innovations in commodity computing. Ars Technica covers similar ground from a rather more technical angle.

Fast software

• Paul Hsieh's page - information about how graphics accelerators work, how to write fast programs on the Pentium 2, and suchlike.
• The nVidia Developer's Resources; how to get spectacular effects using OpenGL and the incredible hardware accelerators currently available.
• FFTW - almost the fastest Fourier transform code around, and certainly the most convenient to use.
• Digital Freespace Optoelectronic Interconnects - chips which communicate by shining lasers at each other in a 3d structure, possibly the only way we'll get to building 3d chips.

Supercomputing

• The 500 most powerful computers in the world
• What the US government wants from a supercomputer: the ASCI 30-Teraflop procurement order

Places to buy hardware

• Dabs Direct - a good range of hardware available, though not the best prices. Free delivery for orders over the Net.
• UK Computer Prices - a meta-search-engine for component prices from British retailers.
• Scan - the company I tend to use. Very competitive prices, £10 +VAT for delivery. Not designed to provide technical support, however.

Not all bosses have pointy hair

• Joel on Software contains lots of very readable documents about the problems of organising software development from an ex-Microsoft manager
• Behind the Scenes at computer-game companies: an indication of what happens if you don't organise your software development, and end up having to work hundred-hour days for months to ship by Christmas

Writing games

• Gamasutra, an on-line magazine for game developers. Everything from how to implement good physics simulation, to how to get venture capital funding. A new article every couple of days, almost all fascinating.