Ada Augusta Byron, Lady Lovelace (1815-52) has been described as the first computer programmer.
She was the daughter of the poet George Gordon Byron. Her mother, who was briefly married to Byron and wanted to stamp out any poetical tendencies in their daughter, encouraged Ada to study mathematics and sciences.
Ada met mathematician/inventor Charles Babbage and was fascinated by his design for the analytical engine, a machine for making numerical calculations. She published an annotated summary of his work, adding (with his approval) several pages of notes on a method for calculating Bernoulli numbers, a sequence of numbers important to number theory.
Lady Lovelace took Babbage's ideas one step further, speculating that the analytical engine could be used for "developping [sic] and tabulating any function whatever," including music composition.
Today, March 24th, is Ada Lovelace Day, an international day of blogging to draw attention to women excelling in technology.
Read about pioneering computer programmer Admiral Grace Hopper and other women scientists at the Women in Science site, sponsored by the San Diego Supercomputer Center.