When I went to UC-Davis (a major bike commute area), I always tried to go faster than everyone else on the road and if anybody passed me, I would run them down. But I had a 3 mile commute at most, so the race never lasted too long.

Now, I'm the only biker I see in the morning and other than the occasional wrong way cyclist in the afternoon, I don't see anyone, so I just try to race the cars and myself. Of course, most of the roads I ride are 40-55 mph speed limits, so I don't keep up very well.