A list of the songs Zep stole from other artists:

from a great webpage: http://www.warr.org/zep.html

• "Babe I'm Gonna Leave You" - A folk song by Anne Bredon, this was originally credited as "traditional, arranged by Jimmy Page," then "words and music by Jimmy Page," and then, following legal action, "Bredon/Page/Plant."
• "Black Mountain Side" - uncredited version of a traditional folk tune previously recorded by Bert Jansch.
• "Bring It On Home" - the first section is an uncredited cover of the Willie Dixon tune (as performed by the imposter Sonny Boy Williamson).
• "Communication Breakdown" - apparently derived from Eddie Cochran's "Nervous Breakdown."
• "Custard Pie" - uncredited cover of Bukka White's "Shake 'Em On Down," with lyrics from Sleepy John Estes's "Drop Down Daddy."
• "Dazed And Confused" - uncredited cover of the Jake Holmes song (see The Above Ground Sound Of Jake Holmes).
• "Hats Off To (Roy) Harper" - uncredited version of Bukka White's "Shake 'Em On Down."
• "How Many More Times" - Part one is an uncredited cover of the Howlin' Wolf song (available on numerous compilations). Part two is an uncredited cover of Albert King's "The Hunter."
• "In My Time Of Dying" - uncredited cover of the traditional song (as heard on Bob Dylan's debut).
• "The Lemon Song" - uncredited cover of Howlin' Wolf's "Killing Floor" - Wolf's publisher sued Zeppelin in the early 70's and settled out of court.
• "Moby Dick" - written and first recorded by Sleepy John Estes under the title "The Girl I Love," and later covered by Bobby Parker.
• "Nobody's Fault But Mine" - uncredited cover of the Blind Willie Johnson blues.
• "Since I've Been Lovin' You" - lyrics are the same as Moby Grape's "Never," though the music isn't similar.
• "Stairway To Heaven" - the main guitar line is apparently from "Taurus" by Spirit.
• "White Summer" - uncredited cover of Davey Graham's "She Moved Through The Fair."
• "Whole Lotta Love" - lyrics are from the Willie Dixon blues "You Need Love."

For a lot more on this go to:
http://www.furious.com/perfect/jimmypage.html