Web Development
I buy a lot of books on web-related topics, but few actually get put to use. These are UI and web application development books I've actually turned to or incorporated into my development efforts.
Designing with Web Standards (2nd Edition)VisiBone Browser Book for Web Designers: A Complete Client-Side Technology Memory Jogger for Colors, Fonts, HTML, CSS (Style Sheets), and JavaScriptXSLT 2.0 Programmer's Reference (Programmer to Programmer)
Designing with Web Standards (2nd Edition)
by Jeffrey Zeldman
$31.49
More about the why than the how, which is equally important.
VisiBone Browser Book for Web Designers: A ...
by Bob Stein

If I don't have this at hand, it's sorely missed. A developer is only as good as his/her toolkit and Bob Stein's Browser Book ...
XSLT 2.0 Programmer's Reference (Programmer...
by Michael Kay
$26.39
JavaScript: The Definitive GuideWeb Standards Solutions: The Markup and Style Handbook (Pioneering Series)Bulletproof Web Design: Improving flexibility and protecting against worst-case scenarios with XHTML and CSS
JavaScript: The Definitive Guide
by David Flanagan
$31.49
Web Standards Solutions: The Markup and Sty...
by Dan Cederholm
$23.09
Bulletproof Web Design: Improving flexibili...
by Dan Cederholm
$26.39
Professional SQL Server 2000 Programming (Programmer to Programmer)Programming C#: Building .NET Applications with C#
Professional SQL Server 2000 Programming (P...
by Robert Vieira
$37.79
Outdated, yes, as I've moved on to SQL Server 2005. This was a reference I turned to, however for management topics, SQL, and ...
Programming C#: Building .NET Applications ...
by Jesse Liberty
$29.67
Covers not only C# syntax, but object-oriented programming principles as well.