Grockit is an academic study website which allows students to create profiles and track their learning. It has levels for academy learning (grades 6-12), SAT, GRE, LSAT, and GMAT preparation and review.
The academy section has tutoring and practice tests in all areas of mathematics, from algebra I to calculus and probability and statistics, and Language Arts, including analytic response, comprehension, sentence fluency, and conventions.
In addition to computer adaptive testing, where the computer learns your level and adjusts questions to focus on specific skills, Grockit also has online tutoring group sessions, one on one tutoring, and group study sessions.
Grockit also allows for 'game' type study sessions where you are attempting to answer the most questions correctly in a limited amount of time or pits you against other online learners. You can tag questions you answered incorrectly to review why they were answered incorrectly, focus future review sessions on similar question types, and create a practice test of flagged items, eliminating the need to focus on skills already mastered.
Another cool feature is the video tutoring sessions which are available for SAT and GRE review. The related comment board allows for interaction with other students and tutors about material in the tutoring videos.
The community tab allows users to post questions about the various tests and get feedback from other users on the site.
Grockit truly is an all inclusive online learning community.
Check it out here: GROCKIT