Hey, It's That Guy! / Hey, It's That Voice!: King Crimson borrowed members from or to a number of other prog bands with its various lineup changes, but John Wetton is probably the most prolific outside the band (he was also the lead singer for Asia and UK, just to name a couple.)
Fripp lent his guitar services to other groups on occasions, including:
Throw It In: Gordon Haskell's laughter at the end of "Indoor Games". Also, the spoken part of "Thela Hun Ginjeet" (see Spoken Word in Music in the Main tab).
During the Islands era, Fripp toyed with the idea of recording Crimson songs in different styles than originally conceived; e.g "The Court of the Crimson King" as a Chicago Blues number.