I really need to get back on the Culture books. I've still only read Consider Phlebas, and I've heard some very good things about some of the other books (Use of Weapons in particular).
It's a great series and there isn't really any continuity between books as far as characters are concerned (although the Culture itself appeared to be descending from its zenith during the last book) so you can read them in any order. My favourite overall is Excession, as you get to learn more about how the Minds interact and govern the Culture's affairs. I thought Use of Weapons was the most powerful, but Player of Games has some interesting takes on society, power and language. Inversions is ostensibly a non-Culture book, but well worth a read.
Q. Why do Communists drink herbal tea?
A. Because proper tea is theft.