CNET made a list of top ten geek girls. The first one is Ada Byron, world's first programmer:
Charles Babbage may have invented the programmable computer, but it was Ada Byron (later Ada Lovelace) who is widely credited with writing the first real program for it. She translated Luigi Menabrea's notes on Babbage's machine from Italian, and added her own ideas on how to calculate Bernoulli numbers using the contraption. These notes came to represent the first piece of computer software ever written..