I just found out about Google Insight, which tracks the number of searches for specific terms over time. This might help us track the general state of various RPG lines.

Here are various trends I found for the period on display (starting with 2004):

Call of Cthulhu: About the same, with the exception of a peak in April 2006 (coinciding with the "Dark Corners of the Earth" computer game). The search term is also very popular in Russia, for some reason.
D&D: Down by half
Exalted: Up by 25%
GURPS: Down to a third
RIFTS: Down by half
Savage Worlds: Up by 50%
Shadowrun: Down by half
World of Darkness: Slightly lower than it started, but now about constant

So it does seem that the gaming industry and community is no longer as large as it used to be. But what else can be learned from this tool? Tell me about your favorite armchair analysis using Google Insight!