I have a great deal of respect for City of Heroes and had a blast in there for a time. So with Cryptic Studio's new superheroic title, Champions Online, live it should hold plenty of interest. Interestingly there is only a Windows version (CoH was also out on the Mac).
The graphic style is like cell-shaded 3D, which is very appropriate for the game/genre. Here are a few shots from the MMORPG site's section for the game.
[Screenshots from Champions Online via the MMORPG site]
I didnt ever play the role playing game for Champions, but I had some of the rules and loved the skills-based system, seeing how to generate characters from it.
One interesting thing, if you visit the MMORPG.com site how all the banner-like ads are for a plethora of 'free to play' games - heaps of them...