I play Harley Quinn over at islandkeepers - an insanely active multi-fandom game. Harley and I, along with Selina Kyle and Jonathan Crane (aka Catwoman and Scarecrow!) would LOVE to see Batman, The Joker, and Poison Ivy around!
If DC Comics aren't your thing, we have a thriving group of Marvel kids around (I'm sure Tony Stark would love to see Pepper Potts around, our X-Men group would love to see more of their peers around, and I'm sure Johnny Storm would like to see his sister and the rest of the Fantastic Four).
AND if comic books in general aren't your bag, we have a ton of other fandoms that would love more people around. Like a Sulu for our Star Trek kids, a Princess Leia for our Star Wars group, Angel, Willow, Fred and more for our BtVS/Angel group, more Lost, Supernatural, Heroes, Glee, Dark Angel, Doctor Who, and Torchwood characters and TONS more!