have you ever looked at the helpfiles of adobe? They are the best I've seen so far for computer programs, as they are very detailed and sometimes even explain some background knowledge (color seperation, etc.).
They definitely go further than explaining to somebody who already knows about it in theory, how he can achieve this with the specific adobe program.
So for Adobe-apps, I never needed an extra book so far.

@Fisheye: I agree Lynda.com videos provide a great training. Unfortunately my friend has not a fast internet connection and the CDs are not so cheap.

@sebilar: Adobe Help is a great resource... but many users are simply paper-addict.

@Dan Weaver: very useful resources...