First up: Rainbow Six Vegas. OK, so it's less of a casemod and more of an everything-around-it-mod, but you have to admit: it's pretty amazing. It's Vegas! Built around a PS3! With casinos, and sexy Vegas lighting, and little pedestrians, and more casinos, and even a little SWAT truck for the Rainbow Six lads to kick back in after a job well done.
Second: Assassin's Creed. As you can probably tell. So, so, so fantastic. Both of these are the work of German casemodder Butterkneter, and you can do worse things today than check out his site for other examples of his craft.