If you mean fans that blow out the back, yes I do, two of em, but they aren't very strong.
EDIT: These fans are messed up, half of one blows out and the other half blows in, and the other one doesnt do anything at all. And I keep the side off of my computer, because thats just how cool I am.
EDIT2: Well theres a dumb grate behind the fans, so they hardly blow anything in/out. And I have a fan in the front that blows air in but my HDD is right in front of it, blocking the air. And the grate is curved down, so all of the air being blown out gets pushed down.
Without the grate the one of the fans seems to be really strong, and the other one is okay.