Some data from the 2010 Census results are now available to the public. The Census Bureau has released the resident population for the nation and states, as well as congressional apportionment totals for each state.
Other interesting links:
American Last Names(Discover the ethnic origin and meaning of last names. Find out how surnames are ranked in popularity, how many people in the United States of America bear a particular name, and how the statistics change between 1990 and 2000 US Censuses.)