I've been meaning to have a play with the 3 Rings (think puzzle pirates) Game Gardens API, so I've created a simple game that we used to call "squares" at school as a learning experience with a view ot using the networking layer of the API for a future game. Enough babble..
Kanature - each player takes it in turns to plays lines onto the grid (an island, see below). If you place a line which forms a square you claim the square, 1 point and another go. Try not to set other people up for wins.
Here's a screenie:
Interesting thing about game gardens, they host the mutliplayer server and generate the JNLP. its all really very smooth.
I'm afraid you do have to register to play though. http://www.gamegardens.com/gardens/game_18.jnlp
AI is a little brutal at the moment, though it is beatable.
If anyone's interested I might write a little article on the GG API.