Resources and articles GOTV and voter turnout (canvassing, phone banking) can make a difference:

• FiveThirtyEight.com: On the Road: Grand Junction, Colorado
  

  So if you go out one four-hour walk shift every weekend between now and the election, you’ve generated — on average — six extra votes from people who would not otherwise have voted for your candidate.

• Is “Obama’s Bet” Worth It? – detailed summary of effectiveness of various GOTV tactics
• Yale Research: Get Out the Vote – amazing resource for research done on voter mobilization
• Daily Kos: Phone Canvassing: How effective? – a recent conversation that brings up some of the other things that come out of phone banking (like volunteers)

Oh, and of course, the Call To Action: be sure to check out Obama’s Neighbor-to-Neighbor Voter Contact Tool