I came across this post in Waxy.org on a referal type script called Waxy Links v0.05. This script lets you add referal urls and associate them with a post. The article is dated last June ::: http://www.waxy.org/archive/2002/06/29/waxy_bac.shtml
I also came across this MT forum post on a David Raynes plug-in which grabs additional data from a trackback, such as title, link, and excerpt/description :::
http://www.movabletype.org/cgi-bin/ikonboard/ikonboard.cgi?s=3e03b2d00201ffff;act=ST;f=20;t=11945 and http://mt-plugins.org/archives/entry/pingedurl.php