Back in the early '90s I was all about signatures when I went to conventions. Here are some of my favorites:
Savage Dragon/TMNT, signed by Larsen, Dooney and Laird. In retrospect, I probably shouldn't have had Laird sign this, as there really wasn't a good spot for his signature.
TMNT Adventures Special, signed by Jeff Smith and Stan Sakai. Stan actually draws a cool TMNT back-up story in this issue.
TMNT Adventures 49, signed by Chris Allan, Brian Thomas and Victor Gorelick. Chris actually had this original cover for sale on his table when I had this signed. Wish I had more $ back then..
Usagi Yojimbo #10, signed by Stan Sakai. This was actually one of the first "b&w" TMNT comics I got as a kid, and I read the hell out of it..hence its crappy condition.