These guys are good becasue they give you material to study on your own, and then offer an in person crash class before the exam: http://www.clareinstitute.com/
And these guys are good for online-only prep:
to become and agent: http://www.realestatelicense.com/index-ca.aspx
license renewals for agents: http://licenserenewal.com/index.html
for brokers: http://www.brokerlicense.com/getYourLicense.html
Fortunately I cleared my exam in the first attempt and in my opinion none of the online ones are enough. I referred to couple of other exam books as well besides the online test preparation software.
BTW, I am at the next step and looking to see what all do I need to start my broker firm/mortgage agency. Do you have any pointers on that? How to go about creating a company, what type of company makes more sense etc.?