Most of the good suggestions have been taken by now. If you have the money, you can buy a Fanged Ring from Dragon Magic for 10,000 to grant you the Improved Natural Attack Feat (unarmed strike) without spending a feat, along with another small bonus. If you can get a sorcerer to cast Mighty Wallop (level 1 Races of the Dragon spell) or (better yet) Greater Mighty Wallop (level 3 Races of the Dragon spell) that would boot you up another one or two size categories.