I have just recently found the Specialized Max XXL to be really good. It is the only helmet I could find which fitted me.

For more urban styled helmets, the Nutcase L/XL size is actually as big as some other brands XXL. The Nutcase looks great on some people, on me it makes my head look like a giant mushroom. The Bern Brentwood comes in XXL and XXXL, but it's non-adjustable so make sure you're getting the right size, a bit lighter and sleeker than the Nutcase though. I bought a trek Zone, I think, a few years back that fits ok. My noggin measures 24" and I found the XL bern too small.