Slow play is the obvious one, but I try to not let that bother me. Golf is my down time where I switch off from the stresses of work so I'm generally quite relaxed about it and will jump a hole if I can't get through a group etc. If I cant i'll generally just mess about with a wedge chipping whilst waiting to tee off etc.
The other for me its the golfer who consistently (and only) talks about themselves , their game, and then takes you through every good and bad shot they hit.