I discovered an interesting site the other day, Trendmapper. Basically, this site allows you to set up keyword searches and then launches those against various search engines (Google and MSN right now). When the search engines respond, they give back a count of the rough number of pages the search returns (the "Results 1 - 10 of about 5,500,000 for ..." sort of thing in the upper right corner of a Google search, for instance). Trendmapper stores those page counts and plots the trend for each search over time.

Somebody, not me, had already set up a search term for "Lisp," so I figured it would be interesting to see how it tracks over time and I added it to the Finding Lisp navigation menu. There are rumors that Lisp's popularity is increasing, for instance. This may give us some evidence of that.

One thing I'll tell you is that the link counts can be pretty volatile. In particular, I have done this exact process manually for some marketing research in the past and found that Google's page counts will vary quite a bit from week to week for any given search term. I have no idea what drives this. It may be some internal garbage collection process inside the Google engine that periodically clears out old links or adds new links. So, take this with a grain of salt when reading things from day-to-day. In particular, the Lisp search term was just added to Trendmapper a few days ago and doesn't have too much history behind it. Today, March 31, 2005, the trend line suggests that Lisp popularity is going down. This simply indicates that, for the moment, Google isn't reporting a bunch of Lisp pages that it had a few days ago, for whatever reason. The reverse is also true, however. If you see a sudden surge in Lisp popularity next week, it's probably driven by some internal Google mojo, not that Lisp itself went through some sort of one-week revival.