This just in:
I hadn’t realized until informed by a friend, that Stan also appeared in The Princesses Diaries 2, so I'm now adding in that cameo as well.
Oh, and I also found him on an episode of the TV show, Nikita in an episode entitled The Guardian.
There is a list of his appearances over on IMDB but most of them are as voice (in animated shows or as the narrator), and some are “real life” appearances (on talk shows, interviews or documentaries), with a few being actual cameos in dramas or comedies. I’ve posted as many as I found. If anyone knows of more Stan cameos, please feel free to suggest them and (if I can find them), I’ll add them to this list.