Ability to create your own avatar... Maybe like the wii's mii. Something you could build and clothe? And MAYBE even avatar monsters for our bad guys! I love the concept of bad guys!
There definitely needs to be an avatar builder and unlock-able rewards for the avatar to use. This level of visualization is critical to many who look to visual reminders of progress for reassurance and to those who are driven by competitiveness. Plus...it is fun.
I would like it even more if it was getting greater when you get levels. Maybe it could be in some kind of 2d environnment also where you can display your achievements.