Myfico.com developed a FICO score estimator. It asks you simple questions and derives a most possible range of your credit score.
I took a try myself. By answering less than 10 simple questions, the site thinks my score range should be 660 to 710 (Fair-Good), which is right. (My score from eloan.com is 663 as of October 23.)
This site is definitely worth a try if one does not know and does not want to pay for getting to know his/her credit score. It should take less than 3 minutes.
(This post is part of PFBlog Product Review series. Check out more reviews here.)