The Fantasy Flight website is pretty sketchy, hardly worth a visit.
But the Kosmos website is excellent, with lots of stuff (in English too): images of every card in the game, complete ruleset, material about the designer and the artists, and a forum (German language sadly).
There is a busy fansite, mostly in German, though it does include an English-language forum. It's worth checking out this thread for fan-designed cardsets.
At Blue Moon Liga you can play online using software called CardTable.
Chris Dearlove looks after an extensive FAQ.
On BoardGameGeek Brad Durandetta is promising us a deck-by-deck strategy guide. The first one, on the Hoax, is invaluable.
The Blue Moon deck database, a deck-building aid, is clunky - don't bother.
Some of the best reviews:
A long time ago Richard Huzzey reviewed the basic set very thoroughly on Games Journal.
Last month Joe Gola's magisterial review did what all the best reviews do - made me want to go and play it again immediately!
And a week later Shannon Appelcline did an insightful article analyzing Blue Moon in turn as an Auction game, a Resource Managament game, and a Card game.