Muslim heritage is an intriguing and rather pretty website detailing contributions of a thousand years. Make sure to see the timelineand events sections. Their new "weblog" seems to be shaping up to be interesting too, have a rummage.
Ever wondered about Islamic law? This site hosts a series of essays and papers on various areas by Mohammad H. Kamali and others on topics such as Freedom of Expression in Islam and critiques of contemporary attempts at huddud implementation. All nicely indepth and referenced, some good, some not so good, but all intriguing.