Free Online Practice Tests for SAT/ACT/ASVAB/GED and many others.
Here are links to websites that provide free practice tests for many varieties of test.
Free Test Online - Standardized Tests Math and Science Practice for ACT, CLEP, CMAT, GED, GRE, PSAT, SAT.
GED Free Practice Tests Has free practice tests, but the full program requires fee payment.
Khan Academy SAT practice Personalized practice, anytime, anywhere—for FREE.
Number2.com Free registration required to use the practice tests; focused on the ACT and GRE, with vocabulary assistance.
Prep Factory Free registration required to use the practice tests; focused on the ACT and SAT
Test Prep Review From ACT to Wonderlic, practice tests available include ASVAB, CLEP, CNA, CPA, GED, GRE, and SAT, among many others.