I guess I should show you what I’m working on:
It contains some simple, and some not-so-simple multiplayer online games:
- Cyber Battles (it is clone of Chaos / Cyberwars, in case you know it)
- Checkers, Connect Four, Reversi
The games are multiplayer, so you’ll probably have to open 2 browser windows to try them 
Cyber Battles can be also played single player, but it’s not much fun this way.