In 2006, thousands viewed this chart on ThisIsIndexed. Then in 2008, thousands viewed the below chart on GraphJam, inspired by the one from ThisIsIndexed and created by a Felix. Over this past weekend, Miss Cellanea posted the graph without linking to the original GraphJam page (but thanking one of the millions of Joe’s in the world). Then came über-blogger Andrew Sullivan, who posted the chart today citing Cellanea. No doubt some millions have now seen it.
My conclusion: Always link to your source. And eventually, good content gets recognized.