Three Olives is pretty good, the bartenders at the local bar I go to always want that when I buy us shots. Usually go with the Mango, it is smooth and tastes pretty damn good.
If you like regular Vodka, I suggest Tito's. It is made in Austin Tx and just f'ing rocks.... (BTW, when I say f'ing, that is fucking, not Effin as in the Vodka).
I reccomend Svedka, vodka of Sweden! It got voted number 2 best Vodka several years in a row after Grey Goose, you get a lot of the price, it isn't bad quality, awesome possum!