Try out the Census Bureau's new mapping feature. . .
(Click to Enlarge)
The Census Bureau has an interactive 2010 population map up on their website. Not all the data appears to be available yet, but it looks like it may be a useful tool as more data is released. You can check it out by clicking here. The map you see here was produced in this tool. On the interactive map you can hover over the county and see the actual population.