The Economic Policy Institute's State of Working America offers a wealth of resources on the economy and inequality. Like the question of who gains when income grows (or loses when it drops).
It's no secret that income inequality has grown, but there's just something about an interactive infographic that lets you trace it year by year, comparing for instance the periods between 1949 and 1978 and 1979 and 2008 and seeing the blue wedge of the pie chart, the part representing the bottom 90 percent, go from the majority of the earlier chart to nonexistent in the later one.
Consider this a reminder in case you were forgetting why you should be angry about income inequality.