I love playing around with Hero Machine Alpha, and at this moment, I've got the urge to experiment. If anyone would like me to design a Hero Machine model of their character, let me know. I'll probably be at it for about an hour, so act quickly!

Limitations: Unfortunately, Hero Machine has it's downfalls. 

Kids (no child body types)
Non-muscular body builds (tend to be difficult, but not entirely impossible. 

Superheroes are probably your best bet. I also love making aliens!