For everyone who appreciates the classic Gang of Four book
Sour (stingy me?) point: as this was on my personal weekend reading list, value comes to mind: As with many of the shorter niche tech books these days, I find myself put off some by the $44.99 list price for just under 260 pages of content. By comparison, the very concise and in-depth Pro C# 2008 and the .NET #.5 Platform
by Andrew Troelsen lists at a fair $59.99 for 1,370 pages of awesome content. Granted, both books can be had for less from any book discounter, and Apress offers an eBook format for $23.
Some of the books' content from the publisher:
Hope this helps!