BrettspielWelt
I haven’t finished my review of Dominion yet but as you can probably tell, I like the game a lot (having already mentioned it a couple of times). At any rate while checking it out on BBG I saw that there is an online version of it at BrettspielWelt. I have since gone to the German site and played several games of Dominion. If you’re ever bored I highly recommend it, or any of their other games.