Great, old concerts you can stream in high quality
pitchfork.com
pitchfork.com
SugarMegs[0] has an amazing collection of bootlegs. Be prepared to spend days there! It seems to be mostly rock, but also there's a lot of funk, jazz and who knows what else there, from 1930s to present day. e.g. Hundreds of Hendrix gigs. Hundreds of Miles, Coltrane, Keith Jarrett gigs.
Also, everything has a setlist page with tunes, musicians, sometimes the story of the gig etc, which is nice. They appreciate it if you can fill in unknown tunes, fix incorrect details etc. Send them the corrected HTML setlist pages. I started doing that because I felt I owed them so much.
Sound quality varies.. it's lossy too, but the music comes from DIME[1], a private torrent site you can join free and download highest possible quality audio and video. (SugarMegs is audio only). It seems they remove anything that's commercially available from their site, and respect some musicians' wishes to not have their bootlegs distributed anywhere.
[0] search page: http://tela.sugarmegs.org/
[1] http://www.dimeadozen.org/
[2] https://archive.org/browse.php?collection=etree&field=creato...
We live in privileged times, where we can hear greats from over 100 years of performing history. It's a double-edged sword, though; in the old days, the guy down the street who played the fiddle was enjoyable to listen to, because you couldn't listen to Heifetz or Kreisler on demand, where now, every amateur is compared to the greats of an entire century. It's made amateur music-making less enjoyable for a lot of people.
For some bands, maybe.
Others, such as my personal favorite (Nine Inch Nails) have well-organized fan sites with easy to access archives of just about every recording ever known to exist for the artist.
I can't remember what their old club was called. I remember being a member of that used to unlock a real trove. But their old web sites were always intentionally confusing and maze-like in an entertaining and mysterious way.