I just discovered a tremendous research source for students (and anybody else) who are curious about changes in income inequality, growth, health, education, etc. in America over a 90+ year period. It’s very flexible and interactive with graphs, etc. It’s The State of Working America, published by Economic Policy Institute. It has tremendous library of both static graphs from up-to-date data, but also some Flash-based interactive graphs such as the following on how income growth has been shared in the U.S. since 1917. This is just a screen shot here, but you should definitely go to the site itself and play with it at http://www.stateofworkingamerica.org/pages/interactive#/?start=1917&end=2007.
The best part is it is entirely Creative Commons licensed, so people can feel free to save copies of the images and re-use them without violating copyright (just remember to give credit to EPI and State of Working America).
This is a very, very useful site. It’s on par with Hans Rosling’s Gapminder.org, and that’s very high praise indeed.