Few men and even fewer women are inclined to do repetitive, emotionless tasks
Editing Wikipedia or writing code should not be a repetitive, emotionless task. Wikipedia makes it such, which is one reason I don't edit it any more, but I started my own little wiki recently (wiki.world3.net, view recent changes because the front page isn't done yet) and am really enjoying adding content to it. Similarly I enjoy writing code for my own personal projects, and even at work much of the time.
There is something wrong with Wikipedia and FOSS projects that makes them unpleasant. I'd go as far as to say that Wikipedia doesn't just put off women, it puts off a lot of men who aren't willing to fight the bullshit constantly.