A site that I run has a guestbook on it. Over the evening, someone left some very nasty messages. I removed one of them that was about 2 minutes old (not a lot of traffic - so nobody missed it). But the first one was up since 10pm last night - so it had to stay. I feel funny moderating the guestbook, but I know that the message was left by a rival site (which isn't too professional if you ask me).

I have the IP of the person (who posted twice under 2 different names but had the same IP). Is there any investigating I can do to find out any bits of info? I looked into one of the domains listed in an email address that the person used, but I'm guessing the email address is fake too....

They weren't vulger, so I'm not looking to contact his/her ISP, but I just want to see if I can get any clues. BTW, I blocked this person's IP from posting again. I'm thinking it was someone with a cable modem since both messages were left outside of work hours. Someone has REALLY got to hate us to logon to our site at 6am before work (and 10pm the night prior) just to talk smack!