I play Dean Winchester over at islandkeepers - an insanely active multi-fandom RPG. I'd really love to see Madison (the werewolf chick), Meg Masters, CASTIEL, JO HARVELLE, Ellen Harvelle, Bobby Singer, and pretty much any and everyone from the show. I'd love an adult John and Mary Winchester around, and JESS would be awesome, too. I'm sure our Sam would love to see these guys around, too!
I also play Spike, and I'd really like to see Angel, Drusilla, Fred/Illyria, Cordelia, and Faith there. We already have a Buffy and a Connor.
Annnd I also play Jason Teague from Smallville, so Lana Lang would be great!