George is the colonel and Ruth's adopted son, he's played by Sam Saletta and is one of my favorite characters on 7H, even though he's not featuerd very often.
George was first introduced in episode #14 (season 1), and according to episode guides, his last appearance was somewhere in the beginning of season 6.

So it's been quite a while now, and I was just wondering why don't they show him anymore. Was he written off in some sord of way? It'd be really cool to see him again.

I don't know. I was actually wondering the same thing the other day. I don't remember an episode, where they "said good-bye George" or whatever, so maybe they are just waiting for a good time to bring him back.