When I did the ME exam, I got the information from the NCEES with typical exam questions, etc. Once you know the kind and general scope of questions asked, your college textbooks should furnish the remainder of what you need.
There is also a "How to Improve Myself to Get Ahead in My Work" forum under "Corporate Survival" on this site- these kinds of questions pop up there as well.
I used the reference manual to study for the PE exam, and thought it was pretty good (at least I passed). It has good example problems that are somewhat similar to what you see on the PE exam (definitely brush up on your combustion calculations and heat and material balances for the exam).
The fifth addition had about 15 chapters, and that was about how many weeks I had before the exam. I just spent an hour or two every other night reading through and understanding the problems at approximately one chapter per week.
The practice exams are good for the last couple of weeks just to get back in the practice of taking a test.
