Suggestions below. Not all are amazing sound quality, but as a music fan first, Hi Fi fan second, I can happily put up with that:
Various: Jazz on a Summers Day
Errol Garner: Concert by the Sea
Muddy Waters: Muddy "Mississippi" Waters Live
Bob Marley and the Wailers: Live!
Curtis Mayfield: Curtis/Live
James Brown: Live at the Apollo Vol II
Parliament/Funkadelic/George Clinton: Live from Houston
The Band +Various: The Last Waltz
Bob Dylan: Live 1964
Bob Dylan; Live 1966
Bob Dylan/The Band: Before the Flood
Bob Dylan: Live 1975
Bob Dylan: Hard Rain
Jefferson Airplane: Bless its Pointed Little Head
The Who: Live at Leeds
Crosby, Stills, Nash & Young: 4 Way Street (A definitive version of 'On the Way Home' - Oh how I long for decent quality Buffalo Springfield live recordings)
Johnny Cash: At Folsom Prison
Johnny Cash: At San Quentin
Neil Young/Crazy Horse: At the Fillmore 1970
Neil Young: Time Fades Away
Neil Young: Live Rust
Neil Young: Unplugged
Bruce Springsteen and the E Street Band: Hammersmith Odeon, '75
Talking Heads: The Name Of This Band Is (2004 expanded version)
Jeff Buckley: Live at Sin-E
Portishead: Roseland NYC live
Sigur Ros: Heima
BBC website / red button over the festival period
I assume we can't discuss live bootlegs so these are only official releases
c'est la vie