There is an awesome set on the PSA Registry:
http://www.psacard.com/psasetregistr...t.aspx?s=34713
The cards other than Gibson, Palmer, Robinson, and Snider are scarce and were created for special promotional signing events. It's likely that there are un-autographed specimens floating around that didn't get signed at the events, but these are probably even rarer than the signed versions. --tim