dnsstuff.com had an abuse lookup, but it's under maintenance right now, but has some other tools to check the records (which won't apply if you are getting any mail at all).

mxtoolbox.com checks something like 140 lists for you, it's free. You need the IP of the mail server, but it gets that for you too. Do a MX lookup on the first screen, when those results come back, click on blacklists.

Check a header of a mail that goes through to make sure it's coming from the IP the mx lookup is returning, try that IP too if it's different.