I bought the premium membership during my bachelor's degree many years ago and continue to use Accounting Coach as a reviewer from time to time. Let me tell you this - you do not need to spend any money to peruse through the database but I highly recommend it. The access is very cheap and you get a lot of template forms, quizzes, videos, and many other little perks for a one time fee.
One of the wonderful things about this membership is that you can move back and forth between topics; this is especially helpful for those who are more self paced or have a busier day. There are some certificates of achievement if you feel like challenging yourself, but the real thing about this is the wealth of information (at your pace) you can obtain.
There are other venues online as well, but AccountingCoach does a great job at covering most bases.