How is Volity different from them? What can we learn from them, just the same?
Probably the most famous and most-used board game site on the Net. Lots and lots of games, all written in Java and Web-accessible. You can use a free Yahoo account as an ID across all of them. Very easy to jump in and starting playing anything.
Our user story of parlor->table->seat is largely thanks to Yahoo Games' structure.
However, the network of games themselves is proprietary and closed. Nobody can extend the system by adding their own games. There doesn't seem to be a way to profile players in general, either; only within the context of a certain game. (In other words, you can see how well Bob does at Chess, but you can't easily see what other Yahoo games Bob likes to play.)
http://www.brettspielwelt.de/gate/jsp/base/
A German (but internationally aware) site featuring online versions of popular European board games.
In the abstract, this project is quite similar to Volity. Launched around 2002-2003, it seems to have found success at starting a vibrant community of game players and creators. Like Volity, it uses open protocols to let anyone run game hosts on their own Internet-connected machines. Its website makes it easy to find and join active games.
That said, it does not seem to have quite the broad reach that Volity aims for. Games are programmed in a custom language and seem to use a similarly custom network protocol. Graphical client software is available only for Windows.
Its userbase seems to skew young and male, compared to the other projects listed here. This is interesting insofar as I'd like to see Volity reach beyond the traditional "gamer" demographic from the get-go, if possible.
http://www.daysofwonder.com/index.php?t=play
Like BSW, a showcase for online versions of board games -- in this case, only a handful of titles from a single publisher. Notable for applying a common user account across all available games (with the ability to easily view other peoples' cross-game histories) and its automated use of an ELO score system.
A complete and mature platform for Interent-based game play, but of a more DIY bent than Volity. Instead of being guided by an automated referee, VASSAL games are entirely manually driven, just as face-to-face boardgames are. The protocol is geared towards little more than exchange of visual component (board, card, counter) information among the players.
It also seems to be largely aimed at wargame players and designers.
http://www.zillions-of-games.com/
A commercial, proprietary, Windows-only product featuring its own game authoring system. If I understand its website correctly, it can also automatically generate bot opponents, which is pretty nifty.
Seems to be focused on board games, and only board games. (Or puzzles that can be visually represented like board games.)