Transformers Universe has just begun accepting sign-ups for beta testing. To register, head on over to the official website and choose your allegiance.
Transformers Universe is a free-to-play title by Jagex that's aiming for a browser client release. Players will duke it out as Autobots and Decepticons. While Earth is going to be the original battleground, the game will eventually expand to the stars and beyond.
[Thanks to savvy reader Jeremy for the tip!]