Here is a list of some GMAT material I have come across that should help you out in your studies. Some of the stuff I found on the TM Forum, and some on other areas of the internet. I tried to add some of the files that I see that people ask about the most. Some of the links where you could previously get these files are no longer working, and I know it is a hassle for the people who do have them to constantly email them to those who ask.
Clintonn Notes & More - Zip File
OG 11 Sentence Correction Q's.pdf
OG 11 Critical Reasoning Q's.pdf
OG 10 with Explantions PDF - Verbal only
OG 10 Problem Difficulty Levels - Excel File
GMAT PAPER TESTS SETS 1-20.zip
GMAT PAPER TEST SETS 21-31.zip
1000 Reading Comprehension Q's.doc
1000 Critical Reasoning Q's.doc
A Template Approach to the GMAT Essay.doc
GMAT Grammar Notes by PSahil.pdf
Spidey's SC Notes.pdf (Really Good)
Permutations - Some helpful info on Combinatorics - Doc
Would be happy to add any files that you guys would feel helpful. Will try and host these files as long as possible.
Good luck.