Here's an idea -  instead of emailing the report, post it on Twitter: "@arikfr 152 of your followers look spammy, while another 3334 look follow-worthy! <a href="http://www.followham.com/show.php?username=arikfr" rel="nofollow">http://www.followham.com/show.php?username=arikfr</a><p>This way you gain two things -
1. More users will try the service (giving away Twitter username is easier than giving away email address).
2. More chances that people will RT this messages and spread the word about the service.<p>And as @dschobel mentioned - you should register @followham.