Listmania!
Web Design / Web Development MUST HAVE Books
JavaScript: The Definitive GuideJavaScript: The Definitive Guide by David Flanagan
Buy new: £22.24 / Used from: £15.97
The bible of Javascript. I own the 2002 edition, but there's an updated one
Essential ActionScript 2.0Essential ActionScript 2.0 by Colin Moock
Buy used from: £3.19
Best ActionScript book around. For flash developers.
Don't Make Me Think!: A Common Sense Approach to Web UsabilityDon't Make Me Think!: A Common Sense Approach to Web Usability by Steve Krug
Buy new: £12.46 / Used from: £13.67
Serious about Usability? Get this!
Eric Meyer on CSS (Voices (New Riders))Eric Meyer on CSS (Voices (New Riders)) by Eric Meyer
Buy new: £24.51 / Used from: £5.00
From the CSS Guru. Great resource.
More Eric Meyer on CSS (Voices That Matter)More Eric Meyer on CSS (Voices That Matter) by Eric Meyer
Buy new: £20.15 / Used from: £3.80
It complements the book above.
Programming Flex 2: The Comprehensive Guide to Creating Rich Internet Applications with Adobe FlexProgramming Flex 2: The Comprehensive Guide to Creating Rich Internet Applications with Adobe Flex by Chafic Kazoun
Buy new: £36.13 / Used from: £1.62
The Evolution of the ActionScript Language. You can now use it on Flex 2.0 and the next generation of Flash.
Programming PHPProgramming PHP by Rasmus Lerdorf
Buy new: £16.90 / Used from: £15.75
Good resource for PHP 5
Professional ASP.NET 2.0 (Programmer to Programmer)Professional ASP.NET 2.0 (Programmer to Programmer) by Bill Evjen
Buy new: £27.19 / Used from: £2.90
Get to grips with ASP.NET 2.0
Build Your Own Ajax Web ApplicationsBuild Your Own Ajax Web Applications by Matthew Eernisse
Buy new: £18.04 / Used from: £6.44
Ajax from the Sitepoint website guys!
Transcending CSS: The Fine Art of Web Design (Voices That Matter)Transcending CSS: The Fine Art of Web Design (Voices That Matter) by Andy Clarke
Buy new: £17.99 / Used from: £23.03
Probably the best advanced XHTML/CSS book around