Practice exams for driving tests are available online through DMV.org and Driving-Tests.org. Free practice questions are available on both sites, and DMV.org also has paid options.
DMV.org has a short, free practice test available to anyone plus two tiers of paid options, along with a for-purchase fact sheet. The paid options include unlimited practice tests of 50 or 100 questions.
Driving-Tests.org has practice tests for each state. Users choose their state and can choose among a variety of tests, including permit and sign tests. The site also has motorcycle license and CDL practice tests. Handbooks for additional study are included in the resources provided by the site.