Susan Oxnevads Blog has some great tools and she provides oodles of well-organized details on the tools she recommends.
In this case she is recommending Flubaroo. A terrific script that a I have used to make Google Forms into a self-grading quiz or test. Not as robust as other tools designed as quizzing tools (Quizstar...), but it works. The only issue I came across was a difficulty in setting up the automated email back to the student with their results. Other than that it works peachilly.
Avi