I'm not one to promote online petitions but I'm making an exception in this case.
I never knew that Alan Turing was gay, had been found guilty of being gay and forced in to chemical castration to avoid a prison sentence, following which he committed suicide a couple of years later. Bearing in mind the major factor he played in ending WWII I find it unbelievable he hasn't been given a posthumous pardon. A knighthood would be nice as well.
http://petitions.number10.gov.uk/turing/