I thought player race based houses/castles would be a cool idea has anyone done this?

You mean like, an Argonian swamp house or something? That'd be cool, and I don't think it's been done.

yes thats what i meant I havent found anything like it but i thought it would be pretty cool

http://oblivionsrealestate.com/ have a number of homes that are based on, well, maybe not so much the race of the player but definitely on the player's class. Woodelf ranger? Live in a tree in the forrest. And so on.

What exactly be the different between a redguard's house and a breton house? Class maybe, but race? o_O

well lore-wise Redgaurds tend to be more Adventurers and Sailors and Bretons tend to be mages

but i didnt really mean human races as much as i meant Beast races, Elves, and Orcs

Just browse ORE and you should find something suitable for anyone really.