Legally, bicyclists are supposed to follow the rules of the road and stop for redlights and stop signs.

I pretty much always stop for red lights. If it's a big enough intersection to warrant a light & not just a stop sign, I'll stop and make sure there's noone coming.

I usually stop for stop signs, Stop signs can sometimes be optional if it's a 4 way stop and I've got good visibility coming to the stop to see that there are no cars coming in any of the directions. I will still at least slow down and make it obvious that I'm looking around. It does suck losing the momentum when you have to stop.