Good sounding 70's live LPs...

At the Fillmore - Humble Pie
Reckoning - Grateful Dead
Live at the Roxy - Zappa
In New York - Zappa
Live at the El Mocambo - Elvis Costello
Live in the Air Age - BeBop Deluxe
Take No Prisoners - Lou Reed
Live (more or less) - Richard Thompson (I have 5 copies it's that good)
Time Fades Away - Neil Young (one of the few rock live albums I know of that featured all new never before recorded songs)

Can't remember, but I also think this one is from the '70s:

Stations of the Cross - Johnny Thunders

I'm also a big fan of Tom Wait's Nighthawks at the Diner.

Let's see....

Renaissance "Live at Carnegie Hall"
Steeleye Span "Live at Last"
Fairport Convention "Live" and "Farewell, Farewell"
Joan Armatrading - "Stepping Out"
Joni Mitchell - "Miles of Aisles"
Mike Oldfield - damn... cant't think of the name... oh yeah - "Exposed"
Bruce Cockburn "Circles in the Stream"

Lou Reed - Rock & Roll Animal

I can second Audiofeil's recommendation on the live Waiting for Columbus album by Little Feat. I have an orginal Warner Bros. pressing and it is excellent. Also like Genesis' "Seconds Out" live double album at a concert they gave in Paris.--Mrmitch