I have been having several visits to my site from keywordspy. From what I gather, you can enter a URL and learn what keywords they are using for things like Adwords, etc.
My site is very new and small but is slowly getting traffic. For the past month I've started running Adwords on a very small budget. My traffic has grown to just over 1000 visitors per month and have made a grand total of $9.00 in a month of Adsense.
I guess I'm curious to know why someone would spy on such a small potato. Also, when I went to the site to spy on myself, none of the keywords were ones I'm using, and make no sense.