I have a Giro Atmose helmet. It's well vented, but too round. The thing leave dents in my forehead the moment I put it on. Ugh.
My next helmet will (probably) be the Trek Women's Circuit helmet. I tried one on in the local store, and it fit! Couldn't believe how comfortable it was. Guess I'm also an oblong head, though I never thought of it that way. The atmos bulges at the sides of my head and I have to over-tighten to compensate.
http://store.trekbikes.com/jump.jsp?...&bShopOnline=1
A very pretty color too. But I do love teal.