Feel free to add some of your own trivia:

The first time Led Zeppelin's Jimmy Page,John Bonham and John Paul Jones played together was as studio musicians backing for Donovan's song "Hurdy - Gurdy Man"

Stephen Stills went with his friend Peter Tork to an audition to become a Monkee

The background singers for Lou Christie's "Lightning Strikes" were the Angels,who had a hit with "My boyfriend's back"

Van Morrison's song "Brown eyed girl" was originally titled "Brown skinned girl" but was changed to be more acceptable on AM radio

The Young Rascals were discovered by Sid Bernstein in a Long Island club while he was putting together the Beatles concert at Shea Stadium

According to band legend,the name Alice Cooper came to Vincent Fournier during a Oujia Board session where he was told he was a reincarnation of a 16th century witch of the same name

Paul McCartney is the Kazoo player on Ringo Starr's "You're 16"

The Young Rascals name was inspired by the 1920's "Our Gang" films,later known as "The Little Rascals"

I did not know that about Brown Eyed Girl.

John Lennon played a stolen harmonica on 'Love Me Do', years later returned to the shop and paid the owner for it.

Ringo is credited as a co-writer on the Cream song 'Badge', he only contributed one line.

David Bowie was born David Jones, changed his name to avoid confusion with the ( at the time) more popular Davey Jones of the Monkees.

Bruce Springsteen sings backing vocals on Graham Parker's 'Endless Night' on the Up Escalator LP.

Nils Lofgren best known as Springsteen's guitar player and solo artist played piano on a couple of early Neil Young LPs.

Joe Satriani toured with Deep Purple as lead guitarist, never recorded in studio with the band.

Jimmy Page once owned the residence formerly owned by Alistair Crowley....the famous 'Mr. Crowley' from the Ozzie Osbourne song.

Billy Joel owns a house on the Hamptons formerly owned by the late Roy Scheider from Jaws and Blue Thunder fame. Reportedly Joel has been trying to sell for about $7 million.

The lead guitarist of the Rumour ( Graham Parker's backing band) was Brinsley Schwarz. Who played with Nick Lowe in an earlier band. The name of the band?...."Brinsley Schwarz"...

Speaking of Nick Lowe , he was married to Carlene Carter, daughter of country singer June Carter and step daughter of Johnny Cash. Carlene appears in Nick Lowe's video of 'Cruel To Be Kind', perhaps his biggest hit, as his new bride, which at the time, she was.

...I've got hundreds more...

 

 

Nice list Zilla !!Here's some more:

Crosby,Stills and Nash asked Clapton,Steve Winwood and George harrison to join the band.Neil Young was asked fourth and accepted. 

Mick Fleetwood and Iggy Pop are both featured in Star Trek

Cher was a background vocalist on the Righteous Brother's "You've lost that loving feeling"

Jimmy Page was a session guitarist for Tom Jones' hit "It's not unusual"

Neil Young arrived at Woodstock with Jimi Hendrix and realized it was several miles from the helicoptor pad to the stage.They stole a pick up truck for the journey.Young calls the theft"One of the high points in my life" 

 

There was going to supposedly be a supergroup called HELP. These were just preliminary discussions. Then something happened and it never became a reality. Can you tell me who was supposed to be in that band.

Jessy,that would be Emerson,Lake and Palmer adding Jimi Hendrix who was considering joining them before his death 

Mojo is the man today.

The band that Jorma Kaukonen and Jack Casady formed after Jefferson Airplane was supposed to be named 'Hot Sh#t', they were forced to change it to 'Hot Tuna' at the strong request of the record company and most likely their agent.

Uriah Heep was the first band from the West to perform behind the Iron Curtain. There is a live CD from that tour.

The band that is performing at the frat party in the Rodney Dangerfield movie 'Back To School' is actually Oingo Boingo, not actors pretending to be a rock band.

Speaking of movies ( and soundtracks), before Walter Becker, Donald Fagen and Denny Dias officially named their band Steely Dan, the recorded a soundtrack album for a low budget film....'You've Gotta Walk It, Like You Talk It.'

Chevy Chase played in a band with members of Steely Dan even before they recorded that soundtrack.

Jeff "Skunk" Baxter was a full time member in two major rock bands at the same time....Steely Dan and the Doobie Brothers.

George Harrison guested on stage ( and sang) with Monty Python's Flying Circus as one of the Royal Canadian Mounties in the lumberjack sketch.

Elton John plays piano on one track of the most recent Alice In Chains CD.

The character, Leather Tuscadero,who made a few appearances on Happy Days T.V. show was a real live rocker named Suzi Quatro....she had one hit back in the 70s....'Stumblin' In'...I think was the name of the song.

The late guitarist from the early Ozzy Osbourne band , Randy Rhoades, was originally a member of Quiet Riot.

Sharon Osbourne once managed Queen...

Queen and Aerosmith on the same bill...

And Blake records a few amusing tales of Queen being paired with unlikely bands; namely Lynyrd Skynyrd who, according to drummer Roger Taylor, had their label reps on MCA hold up banners during Queen’s set “that said things like ‘Shit!’ and “Queen Suck!’” In another concert, Queen are paired with Aerosmith and “a row broke out between their respective management over who would play first.” Guitarist Brian May and Aerosmith guitarist Joe Perry, eager to let the politics play out, both got trashed together on a bottle of Jack Daniels before the show. And, as Blake writes, “Come showtime, both guitarists were blind drunk.” In retrospect, it seems silly that there was even a debate over who the bigger band was. (Blake also scores points for writing the best description of Aerosmith and Steven Tyler on record: “Aerosmith were a louche, glammy rock n’ roll band whose lead singer Steven Tyler was an accomplished poser.”)

http://www.queenconcerts.com/detail/live/105/queen-live-01-05-1974-farm-arena-harrisburg-pennsylvania-usa.html

 

Joan Armitrading, Steve Howe, David Bowie and Morgan Fischer all "guested" on Queen albums...