Chris at Mixing Memory (and indeed Gavin at Investigations of a Dog gives his thoughts on the matter) has posted about a psychological study which suggests playing First Person Shooter Games (such as Half-Life and Medal of Honor) improves spatial reasoning abilities, which in turn leads to improvements in mathematical abilities.

Chris also considers the suggestion that women are worse at spatial reasoning than men, and discusses whether the expectation of women being poorer at maths causes them to perform below their potential, and the statistic therefore continues to be perpetuated. Indeed, women who were studied did have weaker spatial reasoning abilites, which improved dramatically by playing these computer games. Something which we may not see substantially in practise however, as we all know a large percentage of these games are both played, and aimed at men.
However, for all those men out there, seeing as it seems playing these games is a good thing, (a statistic I personally didn't need a study for!) maybe next time your wife, girlfriend, mother or sister is berating you for all that time you spend hogging the sofa with your X-box, Playstation or Wii (delete as appropriate), you could always tell them it means you'll have a better head for figures, and therefore can quite easily count exactly how many pairs of shoes are in the wardrobe! ;-)