I've been doing some analysis of the search data from DrupalModules.com.
These are the top 250 Drupal search terms, based on 29,754 user-unique searches performed in the last 4 weeks via the Drupal Modules search box. Font size is proportional to the number of searches made.
Multiple searches for the same term by a single user are only counted a maximum of one time, in order to keep the results as fair as possible. In other words, someone searching for the same thing 100 times in a row will not affect the results.
These results do not include searches made using Module Finder. Due to Module Finder's interactive nature, it does not generate the kind of statistics you get from a normal search box.
Here's a text file with the exact numbers for the top 250, plus a full-size, clickable HTML version of that visualization you see above: