Kirk's bands before Metallica were:

Mesh

The garage band called 'Mesh' was his first band ever.

Exodus

The first band, that won a great reputation in the San Franscisco 'Bay Area' - metalscene. While he was playing in this band, he was getting so much of wicked technique, that Metallica asked him to join the band.

Kirk's projects beside Metallica were:

Spastik Children

San Francisco, CA 1986-1990

The lineup:

 

Fred Cotton - vocals

James Hetfield - drums & vocals

Cliff Burton - bass & vocals

Jim Martin - bass & vocals

James "Flunky" McDaniel - guitar & vocals

 

After Cliff's death Kirk and Jason took over his bass duties

Voodoo Children

Manhatten, NY - 1993

Jason Newsted - bass/vocals

Kirk Hammett - guitar

Tony Prinzivalli - guitar/vocals

Whitey Chrobak - keyboards

Tim Lau - drums

Les Claypool & Kirk Hammett

He recorded one track with Les Claypool from Primus.

Bands Kirk has played live with:

Primus - "Tommy The Cat" & "Master of Puppets"

Portland, OR - December 11, 1990

Kirk played "Tommy the Cat" and "Master of Puppets" together with Primus.

Linda Perry & Kirk Hammett - "Whole Lotta Love"

San Fransisco, CA - XXX, 1997 (?)

Kirk played Led Zeppellins "Whole Lotta Love" together with Linda Perry from the band 4 Non-Blondes at the 'Bay Area Music Awards'. Kirk's guitar sounded a bit more crunchy than the guitar does in the original version of that song. Linda did the vocals and at the end of the song right after she said something like: "Here's Kirk Hammett. Maybe you heard of him. He's in this band called Metallica?", Kirk played a few notes of the "Enter Sandman" riff. It was aired on the local Bay Area alternative radio station Live 105.

Swarm & Kirk Hammett

San Fransisco, CA - March 20, 1999

He played with his friend's band Swarm on March 20 in 1999 in San Fransisco. There have been even made a video of this show.

Kid Rock, Lars Ulrich & Kirk Hammett

Burbanks, CA - XX xx, 2000

Kirk and Lars played "American Badass" with Kid Rock on Jay Lenos' "The Tonight Show". There were 3 guitarists on stage so Kirk just played "co-rythm" and Lars played drums. During the song's bells part, Kid Rock said "This is the twisted brown trucker band with the pioneers of this music: Metallica.". After the song Lars got up, gave Leno a hand shake and hugged kid rock after the commercial break during the 10 second interview lars was on Kid Rock's lap.

Bands Kirk has recorded with:

Septic Death & Kirk Hammett

He played solos for Pushead's band Septic Death.

Pansy Devision - "Headbanger"

Kirk Hammett took part in Pansy Devision's song "Headbanger".

Orbital & Kirk Hammett

Kirk recorded with Orbital a song called "Satan" on the "Spawn" - soundtrack.

Primus - "bonus track"

Kirk played together with Mark Osegueda of Death Angel and Primus on an extra secret track on Primus' album "Anti-Pop".