This unofficial fan site is a pretty complete index of current Scorsese news and old movie history. It's also got a lot of funky trivia that's a ton of fun to read, though without footnotes or sources it's probably best to take it all with a grain of salt. We desperately hope it's true, however, that Neil Diamond did a screen test for the part of Travis Bickle in Taxi Driver.
It is really hard to keep track of all the various pieces of Scorsese's prolific career, but his page at the Internet Movie Database does just that. This is the best place to start for a quick and thorough overview of Scorsese's career. It lists all of his work in front of and behind the camera, including the Alfred Hitchcock-style cameos of himself he has inserted in some of his films.
This site hosted by Michigan State University is a handy reference on Taxi Driver, a film that has to be on any true movie buff's Top 100 list. It's pretty basic, but the archive of contemporary movie reviews of the film is an interesting read. There's also a great collection of sound clips - crank up the speakers and let DeNiro ask if you're talkin' to him all day long.
Scorsese was profiled as part of PBS's American Masters series, which spotlights people at the absolute top of their chosen creative field. This is the web accompaniment to the documentary. It features a brief but informative biography of Scorsese.
Scorsese was awarded the American Film Institute's Life Achievement Award in 1997 - quite an honor for any member of the cinema world. (Previous winners have included Alfred Hitchcock, John Ford and Orson Welles.) AFI's webpage on Scorsese includes his biography, links to his filmography and a gallery of photos.
If you're looking for a short but thorough biography of Scorsese (in addition to this great one here at Shmoop, of course) check out the Biography Channel's exhaustive archive of celebrity biographies. It has a quick and thorough rundown of Scorsese's life, with links to his filmography and photos.