So I use this, a protective beanie...
It's NOT a helmet, and they make that very clear on the website and the warning inside the beanie, but while it's not as good as a helmet, it's better than nothing at all.
I ride slow speeds, cruising by the beach on flat concrete. I dont do any tricks or go on any unpaved terrain. I'm not a fan of traditional helmets and I found myself wanting to wear nothing. When I found this, I decided to give it a try. Definitely not a helmet, but it does add some level of protection in the event my head contacts the pavement. Its snug for my head, as I would be a large most likely in a hat (I'm 6 foot 5, and my head isnt huge but it isnt small either). Its not the most comfortable thing, but it isnt too bad, and I love the concept. The one I went with was the thrashe hat.
I also have a bern, but I hate how bulky it is. It looks so giant, even though it fits snug. I shouldn't care how dorky it looks, but I like being somewhat more discreet when it comes to helmets. I'm 41, and I dont care what anyone thinks of how "cool" I look, but I'm not a fan of bulky helmets. I might wanna try a thousand.
Anyways, check out the link... its certainly an interesting avenue.