John Berry of Agile Partners has written a very interesting article called "Is Slashdot dying?". In it, he shows that the comments per post on Slashdot have decreased about 20-30% in 2005. The article is also very cool because it has some "Web 2.0ish" charts and graphs.
... and it looks like some others loved his graphics. Here is his explanation:
They were initially created in Excel (for OS X), then moved into Photoshop for a little cleanup. The XY-scatter is almost as-is from Excel, but I did redraw the line graph.