Samuel L. Jackson and Frank Oz would be great additions! I may have a lead on Frank Oz doing a signing, too.
Carrie Fisher was certainly memorable. Our brief conversation was a little brusque, but certainly funny. And this was at the end of Celebration 2. I got up at 5AM to get on line from C2 that day. All told, I think I waited about 5 hours or so until I got in to get Carrie Fisher's signatures.
One of the most memorable people I had sign was William Hootkins. What a nice and incredibly funny guy! He was an absolute blast. He was bantering back and forth with Richard LeParmentier at Celebration 2, and they made waiting in lines a lot more tolerable.