I just got 100% Chameleon and the Skeleton Key, but I'm having trouble finding any neat places to go. I remember once in Morrowind when I stumbled across a vault in Vivec filled with armor and gold. Is there anything like that in Oblivion?

No vaults, but it can be fun to explore all the castles and you can always take what you want there and sell it to a fence.

I've you've got full chameleon and the skeleton key, you can go wherever you damn well please. Personally I'd take the opportunity to explore the areas of the castle you don't normally get to see.

The easiest way to make a quick coin is to just rob the mages guild and fighters guild blind, assuming your not joined into them yet. Yeah, you won't get thousands, but its still worth the 20 seconds it takes to steal from them. Castles are fun to search, but i usually dont find anything of interest in them. Oddly enough, I find the best stuff by pickpocketing people. Pickpocket a shopowner while their asleep and you can get a nifty enchanted battleaxe. Or you can just rob the store blind =)

I guess I should have specified that I'm just looking for cool places, not treasure. I have no problems getting money. It just seems that there aren't any unique places other than the handful that are involved in quests.

if u have http://www.tesnexus.com/downloads/file.php?id=16513

there will be vaults in oblivion

Not very cool, but the armory in imperial city can give you a decent amount of gold from fences.