Share 'Top ten hazards of commuter racing?'

Conventional wisdom has it that if you get two cyclists going in the same direction, then you've got a race. I guess everyone likes a bit of competition now and then, but there's a time and place for everything. And I'd suggest that narrow bike paths and busy city streets shared with cyclists of unknown ability are probably not the time/place. So, let's see if we can get together a list of top t…