The only way to stop this is for Obama to win. Obama sticks much closer to the truth, is infinitely less nasty, and IMHO will govern much better. You can do three things:
(1) I will limit myself to one example. McCain is fond of saying Obama will raise your taxes. The truth is that Obama will cut taxes for 80% of Americans, and raise them for about 1%. Futhermore, for the 60% of households that make less than $70,000/year, Obama offers tax cuts 3-25 times larger than McCain (e.g., $567 vs $19 for those under $19,000/year). See http://www.washingtonpost.com/wp-dyn/content/story/2008/06/09/ST2008060900950.html for details.