Wow, I've made a submission for two days in a row, I'm on a roll here!
This one didn't take long either and while it's not as good as the Allison pic, I'm still satisfied with the result, though I should have outlined the straps better. Lisa's original look is so iconic I hope I'm not devaluating it somehow. Eh, I'm still pleased with her hair.
Another thing, it's not in the design but her IQ is lower, not that she's dumber at all but it's less... exaggerated. Allison's at 156 now. Actually, I'm going to have to explain more changes mind you.
Next will probably be either Bart or Sherri&Terri (with bio)
EDIT: Added little detail on Lisa's smile. Sorry for wasting your time.