BrettspielWelt

Though the title sounds like the hot new German game in town, it isn't. Brettspiel is a free online gaming site that features many popular board games. I've seen Carcasonne and Stone Age, and I've played, to this point, 26 games of Dominion - only winning 11. YIKES, tough competition.

BGG has a nice primer on it here. I would recommend checking it out before creating an account because the interface isn't as intuitive as it could be.

I'm BWFoster78 on the site. Look me up.