The following is the most current list (Jan 28 2007) of black listed urls. I realize a number of these domains may be used for completely legit purposes, but they've apparently also been involved in spamming and have made it onto Wikipedia's black list.
This list is maintained outside of this website, not by me. But I use a program to help combat spam that utilizes and updates the list several times a day. If you try and post a URL that contains one of the listed domains, you'll receive a notification that your post contains a blacklisted url, and the board will not let you post until you remove the offending url.
I personally like to use tinyurl.com to cut down the size of long urls, but unfortunately it's on the list. Even I can't post using tinyurl. Sorry, but between zaprap.org and ect.org, I'm getting thousands of spam attempts EVERY DAY. It's unbelievable. So I have to use every weapon I can to battle it, or we'd be overrun with ads for penis growth.
Here's the list, which will change an hour after I post it. ::sigh::