If you use the amazing MTSearch add-on, then here is an awesome companion tool.
Graham has put together a way for you to make a text file (or web page) of the search terms visitors to your site use in the MTSearch tool.
I actually have had difficulty getting it to work, but several others have had great success. If you get it running, be sure and let me know in your comments. Don't be suprised if I start asking you how to get it working for my site!
Enjoy!
UPDATE: Already posted? Dagnabbit! Well, my next post will be better!