No Helmet -- Nice!
I commuted without a helmet yesterday, and it was really nice.
I realized, a couple blocks away from the house, that I had forgotten my helmet (usually it hangs from my commuter's stem-cap so I can't forget it, but this time it was hanging on my MTB after weekend riding). I decided it wasn't worth it to turn around.
It was pretty awesome. It's not that my helmet is uncomfortable, but it's a helmet. Even though it doesn't weigh much, the weight of it makes my head that little bit heavier. The visor obstructs my view that little bit, although only upwards where it doesn't 'matter'. There's lots of ventilation, but it still cuts down on the awesome feeling of breeze through hair.
The only thing I missed was my mirror. But the lack of that (and a helmet) kept me extra vigilant about the risky parts of my commutes (big intersections, freeway&lane crossings, left turns), and that extra vigilance probably made me more safe in the net.
I'm back to the helmet today (and going forward), and the helmet didn't bug me at all, but it sure was nice yesterday to have it off!