Here are the most recent national polls, updated as needed:
DailyKos/SEIU/Public Policy Polling: Romney 49%, Obama 47%
Gallup: Romney 49%, Obama 47%
American Research Group: Romney 48%, Obama 47%
Rasmussen: Obama 48%, Romney 48%
Reuters/Ipsos: Obama 45%, Romney 45%
Washington Times/Zogby: Obama 45%, Romney 45%