Transformice (PC, free)

[PeteJ]

http://transformice.com/en/ChargeurTransformice.swf

Grab the cheese, bring it home. Easy!
A video of it in action - http://www.youtube.com/watch?v=GJReZRji7tg

Be sure to register so you can chat

[SuperBeatBoy]

LoL looks awesome, i'll give it a whirl!

EDIT: Unfortunatly, it keeps timing out for me. The servers must be getting cheesed out. :/

[PeteJ]

Yeah takes a few attempts to get in, but once you're in it is stable.

And yeah, it is awesome

[Matt]

That looks great