Just a note for the World War I buffs amongst you - there's quite an interesting plan by Oxford University to crowdsource a livetweet of the Battle of Arras. More info here: http://ww1centenary.oucs.ox.ac.uk/?p=253
I'm planning to take part and other Wikimedians would be very welcome.
You might notice that the organisers have taken a licensing approach of putting the eventual resource they are creating from this initiative under CC-BY-NC, but nevertheless encouraging participants to digitise their own materials and put them on Commons. So that's 50% right ;-)
Chris