Email Notifier for Website
Automatically get an email notification whenever a search engine crawler (spider/agent/robot) is scanning your website
it is FREE
You need following setups: For PHP setups: you must have PHP 4.1.0 or later installed. For ASP setups: MSXML2.ServerXMLHTTP v4 or v5 must be installed. No Perl script at the moment, sorry.
PLease read their http://www.crawler-alert.net/faq.php