The old timers give the young'ns tips on the 60s.

Savage Grace- "All Along the Watchtower"

I also enthusiastically recommend the Blues Project, thanks to Al for the link to the anthology, as my Projections album is in awful condition. Danny Kalb remains one of my favorite guitarists of all time. Also, any Byrds or Yardbirds (look at the guitarists they had in their group--Beck, Clapton and Page, as I recall) albums. Tim Buckley's Hello Goodbye album and Tom Rush's albums in the folk-rock genre. All of the Pentangle's albums are worth getting (especially for John Renbourne's guitar work). And Vanilla Fudge's album is worth it just for their rendition of the Supremes' hit You Keep Me Hangin' On.

Just a bunch I think I haven't seen mentioned yet. Most of these and the ones already mentioned actually sit astride 1970 but I would guess that is not a hard cut-off date for your purpose.

The Nice
Soft Machine
Gong (the Kevin Ayers era)
Colosseum
Ten Years After
The Crazy World of Arthur Brown
Edgar Broughton Band
Pink Fairies
Tyrannosaurus Rex

One other significant record that reflects the style of the era is the 1972 double album "Something/Anything" by Todd Rundgren.

Here's the next batch worth (some even essential!) to check out.

Kim Fowley (Animal God of the Streets!)
Electric Prunes
Family (the one with Roger Chapman, that is, do not confuse this with the 80's Band that went by the same name!)
Groundhogs
Wisbone Ash
Graham Bond Organization (figure this: Graham Bond, Jack Bruce, Ginger Baker, John McLaughlin, Dick Heckstal-Smith, John Hiseman!)
Electric Flag
Giles, Giles & Fripp (the ones to become King Crimson, a group that hopefully remained on everyone's radar, otherwise they should be mentioned here as well in BIG, DayGlo characters)