DAT Achiever is a downloadable program with practice tests for the DAT. "SNS" would indicate that it is a Survey of Natural Sciences practice test.
I used the Kaplan book (which comes with a CD) for the majority of my studying. I read and made notecards from the entire bio and chem sections and practiced the math sections that I had forgotten. I also read the PAT section but mostly only did PATs from practice tests. I had just recently finished OChem I and II at the time, so I really didn't study at all for this section except for reviewing the basic rxns. I thought Kaplan was pretty good for most of my studying needs.
Aside from Kaplan, I also used DAT Achiever (challenging practice tests but worth it) and Barron's (full of errors-would not recommend!).
Hope this helps! Good luck!