I try to list those helmets that are most practical, simple in design, hopefully comfortable and look good.

1. GIRO   The "Flak" (for men probably) & Makai (womens model) bucket type cycling helmets are the ones i like. Adult sizes available.
    
2. VIGOR HELMETS   Lots of neat helmets. CPSC certified. Models include:
   Vigor "Royal" bicycle helmet.
   Vigor "1080" adult bucket helmet - real nice.
   Vigor "Sequel" bicycle road helmet.
   Vigor "X3" bicycle helmet.
   
    
3. BELL   Check on "Bell Kinghead" helmet for those seeking a large adult size. Wal-mart sells Bell Helmets also. CPSC certified. I like these two groups of bicycle helmets they sell: METROPOLIS & CITI helmet groups.
    

4.  
5. PRO-TEC   Three models i like:
   The Classic model.
   The B2 model.
   The Ace model.
   
    
6. PRYME HELMETS   If you like bucket type helmets the Pryme-8 looks like a nice choice. According to their chart it looks like they sell adult sizes. Pryme 8 helmets meet CPSC requirements for bicycle helmets.
    
7. HELMETS FOR LARGE HEADS   This is a very good page on sources for helmets that might fit a person with a larger than average head.