Rowan Atkinson appears in "Never Say Never Again" as a character that is almost Mr. Bean. It's not really a cameo though.
Minnie Driver had a cameo in "Goldeneye", and Madonna had a small role in one of the Brosnan flicks. Richard Branson also appeared in one of the Brosnan films.
They tried to have a reoccurring comic relief character in Sheriff John W. Pepper but it only lasted two films. He played a sheriff or prison guard in a number of films of that era as well.
That old guy you see in Skyfall who helps him setup the home alone traps was supposed to be Connery, but it didn’t happen.
This isn’t really surprising though, Connery stopped associating himself with bond many years ago, so it’s was unlikely he would ever agree to do a cameo.