External Links

Linux

Debian - my preferred Linux distribution- combines an excellent package management system with some well considered policies on software licences and non-free software.
Free Software Foundation - the home of the GPL and the originators of the Free Software movement. The place to go for a whole suite of utilities which will ease the use and administration of any Unix.
Linux Weekly News - a very useful Linux news site.
Freshmeat
Slashdot
Linux.com
Linux Documentation Project
Plugger - Multimedia plugin for Netscape on Unix which provides support for Quicktime, MPEG, AVI, etc.
linux.org.uk
Ogg Vorbis - MP3 Replacement
Parsec - 3D shoot-em-up for Linux
Linux Performance Tuning
Advogato - Home to diaries of many of the key developers and protagonists of the free software movement. Also interesting exercise in group trust metrics (though I'm still not sure whether it's as scalable as claimed).
Linux ATA Development

Security Focus - - home of BUGTRAQ- many useful resources
CERT
Rootshell.com - Exploits galore. Worth visiting, if only to scare yourself into taking security seriously.
Nessus - A security scanner
Insecure.org
The Abacus Project - Useful set of utilities for intrusion prevention, including a log monitor and port scan detector, amongst others

ATT Research Labs Interesting Pages - Including a Cambridge panorama web-cam and live readings of Cambridge weather from the roof of the building. (Oh, and another coffee machine)
Cambridge University
Trinity Hall - The best of the Cambridge Colleges?
Cambridge Pubs - ... it would seem we're not short of them

www.phlebas.com - Nice site, with some interviews with Iain, reviews, et al.
http://www.marathon.org/story/halo_culture.html - Included mostly out of curiousity- this site examines the similarities between the computer game 'Marathon' and Banks' science fiction novels.
Excession - Some interesting ray traced images of ships/places in the Culture Novels

Netcraft - Home of the most comprehensive webserver survey available.
Zeus Technology - purveyors of exceedingly fast webservers since 1995.
Gyre Technology - a Unix consultancy/software company
Exim - A very powerful MTA from Cambridge University
Domain Name Buyer's Guide - A survey of the various Domain Name registrars- well worth a look if you're considering buying a domain.
Free On Line Dictionary Of Computing
The Jargon File
Unix Guide - Comparison of commands across several major Unices. (Useful for answering questions like "What's the equivalent of 'strace' on Solaris?")
Unix Socket FAQ
Cyc - Possibly the closest yet anyone has to got to an AI. Certainly a company to keep your eye on.

Currency Convertor
Ordnance Survey Maps of the UK
More online maps of the UK
The Microship Project
fuckedcompany.com - News and rumours of companies on the edge of the abyss...
The Doomsday Algorithm - How to work what day of the week any date is (in your head...)

CNet News - A general computing news site
The Register - irreverent news site, and current home of the BOFH archives.
The Standard - "Intelligence for the internet economy"? hmmm. Well- a few useful articles at least.
Red Herring - Tech Industry analysts

Electronic Frontier Foundation
Cryptome - "Cryptome welcomes documents for publication that are prohibited by governments worldwide, in particular material on cryptology, dual-use technologies, national security and intelligence -- open, secret and classified documents -- but not limited to those."
Guerilla.net
Software Patent Working Group of the FFII - Invaluable (and comprehensive) resources, articles and links related to the European software patent debate
Alternative Dispute Resolution Services Ltd - Arbitration services - a faster, cheaper alternative to all out war in the courts.