As we wanted to have some simple games for everybody on our TeamSpeak 3 server I was searching and run onto http://www.poolgameonline.com/. A pretty simple site where you can download this game easily. It's called Pool Game Online. After installing it you'll be asked for username and password so register quickly. You don't need to confirm your e-mail or anything so it's pretty quick.
There are many sports and game rooms like snooker, darts, soccer etc. We even created a channel for it so join us. I have 2 wins from two games, not a bad score right?