StraighterLine Offers ACE-approved courses, accepted by all of The Big 3 for college credit. They offer a considerable amount of courses that can be completed quickly. As of February 2016, the cost is $99/month plus $59 (or more) per course taken. Coupons are often available.
Courses are self-paced and most include enough coursework that one can accumulate enough points in the class to pass courses with minimal effort on the proctored final. This allows for quick completion of courses and offers relief for those who don't want to base their entire outcome on a single "pass/fail" exam.