The Federal Government gathers a number of statistics relating to labor and employment, including Industries at a Glance, Unemployment and Occupation. For Employment, look at the Employment by Occupation links, as well as the Job Openings and Labor Turnover Surveys. For Earnings, the Wages by Area and Occupation is a useful dataset, as well as the Employee Benefits set.
Many of these are also available through the Federal Reserve Bank of St. Louis's FRED data interface. Population, Employment and Labor Markets information is available here, in the form of searchable graphs which can be manipulated to show various elements.