Unconventional, pretty bicycle helmets
Personally, I think that good cycling helmets are beautiful. The lines are elegant. The transitions between the surface of the helmet and the vents are graceful. The way that the helmet increases in size from front to back is reminiscent of the wind. They're really quite astounding pieces of technology, if you really look at them. 

On the other hand, cheap bicycle helmets just look bulky and blunt. And the type that most people seem to be linking to, the "brain buckets" that look like skateboarding or horse racing helmets, are just hideously ugly. 

I know that doesn't really answer your question, but as you mentioned ventilation is a big issue and I really think it's worth it to have a good cycling helmet. And there's a big difference in ventilation between a $40 and a $100 helmet. I think if you drop the money on a good cycling helmet, you'll be much happier with it than you will with a "fashion" helmet.