I could query whois for a list of IP addresses by piping the list through "xargs -n 1 whois". It would have been rather more complicated if I wanted to query a website.

EDIT: Here's the code in case anyone's curious -- note that most of it is just a list of domain names:

echo anywhere.fm adpinion.com fuzzwich.com slapvid.com versionate.com auctomatic.com buxfer.com heysan.com octopart.com socialmoth.com virtualmin.com weebly.com whitenoisenetworks.com writewith.com xobni.com iilwy.com jamglue.com scribd.com thinkature.com justin.tv audiobeta.com flagr.com inklingmarkets.com snipshot.com sproutsys.com wufoo.com clickfacts.com loopt.com | xargs -n 1 | lam -s 'www.' - | xargs -n 1 host -t a | grep 'has address' | cut -f 4 -d ' ' | xargs -n 1 whois | grep OrgName | sort | uniq -c | sort -srn