First off, pre-dental isn't the best forum for your question, you should head over to the DAT forum, it in itself is a great resource, aside from providing all kinds of feedback regarding study materials:
http://forums.studentdoctor.net/forumdisplay.php?f=70
This is the stickied sample study schedule that includes the resources/books the author (dentalWorks) used:
http://forums.studentdoctor.net/showthread.php?t=719365
Study material's poll, the author also lists previous poll links in his signature:
http://forums.studentdoctor.net/showthread.php?t=879988&highlight=resources
You'll seriously need to go through the DAT forum for individual topics and the materials people found helpful, there will be many opinions, so brace yourself.
You might also consider taking sources (textbooks often) from the list of sources the ADA DAT writers actually used in creating questions for the exam:
http://www.ada.org/sections/educationAndCareers/pdfs/dat_reference_texts.pdf
As well as the test content (see Appendix E):
http://www.ada.org/sections/educationAndCareers/pdfs/dat_examinee_guide.pdf