I used to!
I swore I wouldn't vote this year cos of the lack of live feed (and therefore the ability to form a true opinion of a housemate) and the way C4 closed the forums.
I haven't voted this year, and don't intend to.
I will just say though, its been easy for me to stick to this, cos I don't really like any of them in there enough to make the call. Its been an easy vow to stick to!