I'm assuming you mean people image signatures, otherwise known as a dynamic signature (such as my own). Some people have created their own, or used a site that creates and hosts one for them. I don't know of any of those sites of the top of my head. I know of this topic from back a while ago however:
http://www.eq2interface.com/forums/s...ead.php?t=1116
Also, to search in the forums, it's up on the top bar across the page. *edit* I think I misread what you said. You just didn't know what to search for, right?