There has abeen a ot of discussion on the ASVAB for the Navy: Getting in forum. Here is a link for those who may want more information.
http://www.military.com/ASVAB
You can also practice the ASVAB by asking your recruiter for a NKO account. There's a section where u can download the entire ASVAB bk by ARCO for free [think it's by Petersons.com]. It also supplies the Pilot & Officer exam bks as well.