Ada Lovelace Day is an international day of celebration of the achievements of women in science, technology, engineering and maths. Last year it was in late March, but it is moving to October 7, 2011.
For Ada Lovelace Day in 2010 I wrote an article describing the guided torpedo patent issued to Hedy Lamarr and George Antheil. The research for that article was quite interesting, and I plan to do a similar writeup this year.