Christopher Doyle has a fun little widget on his Reasonably Clever website called the "Buy-Me-Mizer".
It's more or less a minifig generator from several predefined minifigure parts. You have the ability to change the hair, facial expression, torso, legs, and accessories to suit your purposes. Once you're done you can buy the fig from Chris using PayPal!
I've used his "Mini-Mizer" to create a sig fig avatar and it was all good fun. If only I could have bought him at the time...drat!
Enjoy this little bit of afternoon fun and commerce...