Great question - I'm looking forward to seeing some of the posts to come, as I could always look to expand my collection.
I second all of the Coltrane and Davis recommendations from 9.5 fingers. I haven't heard the rest of his recommendations, so I can't say anything about them. Bitches Brew is a classic. I also have a great album "Miles and Coltrane" of the 2 jamming together. It's sweet!
If u haven't seen the movie "Sweet and Lowdown" check it out (also pick up the soundtrack). Sean Penn plays this deadbeat jazz guitarist in the 30's-40's. I'm not a big Penn fan, but he was great in this movie, and the soundtrack is awesome. The guitarist on the soundtrack is a guy names Howard Alden. I just started collecting old Alden material, but here's a good one:
Concord Jazz guitar collective - live recording w/ Howard Alden, Frank Vignola, and Jimmy Bruno on guitars + back-up band
Stanley Clarke (jazz bass guitarist) - Live (1976-1977)
Thelonious Monk - Monk's greatest hits
These 2 aren't really old, but worth mentioning:
Dave Bruebeck quartet - Time Out
Charlie Hunter - I only own one of his albums "Duo", but if you get a chance to see him live, he's awesome. he plays an 8 string guitar (2 lower bass strings) and plays the bass and the lead guitar all by himself. Words cannot express it - you gotta see it live.
I'll drop back in with some blues recommendations later.