Ugh, really, really hate the fact that other people on bikes don't observe the obvious rule of...If you side of the trail, as demarcated by a lane line, is block, YOU need to wait. I should have to brake while you pass them by using the wrong lane. Motorists are bad enough, really hate it when someone else on a bike is also a threat.
This morning I had a dude in a Prius WITH a bike rack on the car pass me FAR too closely on a double parked city street. Oh man, I have a special hatred in my heart for people pretending to a) care about the environment b) ride bicycles...who are just as bad as every other aggressive motorist out there!