Hi WG774,
It looks like your site is being crawled by the bot for
www.alexa.com
Now i'd not choose to add the Alexa tool bar to my own machines, but i'm curious, why do you consider it's attempt to index your site as the actions of a pest?
regards
Memetic
P.S. Looking for your robots.txt file means the bot is being well behaved. The following might be of interest:
http://www.robotstxt.org/wc/exclusion-admin.html