I take any advantage I can get in traffic. Drivers are for the most part oblivious to bikes, and i've been cut off so many times I wouldn't even venture a guess how many. I look both ways at intersections, and if no one is coming, I don't stop. On the other hand, I try not to be an obtrusive jerk in traffic, because I'm dealing with vehicles that outweigh me 20 to one. The last thing I wan't to do is get into a p!$$ing contest with a skunk. But, yeah, I run lights and stop signs if nobody is around.