I have no idea what the previous poster just said but just get a gogostand (http://www.gogostand.com/). It's a stand that is literally the size of a credit card and you just take it out of your wallet or purse and unfold it and you have a stand that can be used in portrait or landscape mode.
I know you said that you want a case with a stand built-in but I would think a case like that would be bulky and not nearly as flexible as a gogostand. I have one and it's great because I always have it with me in my wallet and it's always there when I need it.
I hear you - I don't like carrying extra stuff around either. The gogostand is perfect for me because I always have my wallet with me but I guess not everyone carries a wallet at all times. Unfortunately, I don't know of any cases with a built-in stand but I'm sure they exist. Good luck!