http://www.startrek.com/startrek/view/news/article/5757.html

Startrek.com has an article about Reagan's visit to the TNG set in 1991 during the filming of "Redemption." It's too bad they couldn't give him a cameo. They could do something so he wouldn't be too instantly recognizable. Maybe Picard could have had occassion to view old footage of a Reagan speech relevant to the situation. That might have been difficult, though. But interesting.

Lucille Ball ran Desilu Studios which first ran Trek. That would have been interesting to have her on TOS, the animateds, or TNG.

I read Milton Berle liked Trek.

Any of the James Bond actors.

Woody Allen as Rasmussen in "A Matter of Time".