There's a rat living in the wall in my house. I need it gone. any ideas?

Fire, and plenty of it. Alternatively, watch http://en.wikipedia.org/wiki/MouseHunt_%28film%29film for ideas.

what's funny is I was thinking about that movie. But fires out of the question because I like my house.

http://www.youtube.com/watch?v=tG51Z_RLwT0

get a trap and use peanut butter as bait, check it until you have a dead rat, always worked for me

I guess I could go under the house and try to put a trap somewhere near the wall(s)

Isolate and exterminate is the best thing I can suggest. If he comes out into your kitchen, then get a glue trap. Had something bumping around in my house and saw a mouse in a room. Used a glue trap with some dog food on it to catch the furry little bugger. Can say one thing, not even a mouse will be stiring in my house this Xmas, since he's in a trash bag, out in the cold, stuck to that glue trap.

I would do that but my dogs/cat would probaly eat it.