Other than the more obvious players (Red, Chris, etc) I would love to see Kip Snip return. I assume that the whole "in prison for the rest of your life" thing was intended to be poetic justice for what he did to Bloo, but it left a slightly sour taste in my mouth, along with the feeling that his character deserved a tad more closure. It would be interesting to see him again, given the strong grudge he now most likely bears against Bloo, Foster's, and possibly all imaginary friends in general.
Old Man Rivers should definitly make a couple of cameo appearences in future episodes, if only to confirm that the writers haven't forgotten that he lives in close proximity to the house.
As for Berry, I'm pretty neutral. She wasn't without her entertainment value, but whenever she reverted to her psychotic mode she was so damn chilling it felt like having a bucketful of ice cubes poured down my spine. Not sure how keen I am to repeat the experience.
