little known musicians we should hear

Since you mention Alejandro Escovedo first (he is so amazing, if it weren't for corporate radio, he'd be a star and "A Man Under the Influence" would be a best selling album), I'll make a few obscure and not so obscure (just in case) additions:

Steve Earle
Lucinda Williams
Joe Ely's "Love and Danger"
The Flatlanders' "More a Legend Than a Band"
Sid Griffin (Western Electric, The Lost Ryders, The Coal Porters)
Gram Parsons
The Golden Palominos' "This Is How It Feels"
Richard Buckner's "Bloomed"
Greg Brown's "Dream Cafe"
Rosanne Cash's "Ten Song Demo"
Wilco's "Being There"
Old 97's
Chris Smither's "Live As I'll Ever Be"
Townes Van Zandt

That's enough for now. Some of these are OOP and you'll have to search ebay and the used bins. Unfortunately, again because of corporate radio, the good die young.
And THANKS for the recommendations from all -- I'll check them out, too!

Yes, Ozfly, Townes Van Zandt & Steve Earle, along with Guy Clark, had a 1995 performance recorded, two years before Townes died. It was released last year, called "Together at the Bluebird Cafe".
Steve Earle once said of Townes that he is the best songwriter out there, "and I'll stand on Bob Dylan's coffee table in my cowboy boots and say it."

LOL
Thanks, Ben.