My favorite, fairly new, rock band is Drive By Truckers. Start with "Southern Rock Opera" and their music just gets better and better after that. If there's any justice left, this group will hit it big soon.
Don't know if they're definitive, but a couple of CD's that I really like, in the Gershwin "pop" vein are:
"Nice Work if You Can Get It" Ella Fitzgerald and Andre Previn do Gershwin and "Someone to Watch Over Me" Susannah McCorkle The Songs of George Gershwin.
If you're really looking for banjo meets heavy metal, try out a group named Iron Horse. They are a bluegrass group that have put out two heavy metal tribute albums. The first was "Fade to Bluegrass" a tribute to Metallica, and "Black & Bluegrass" a tribute to Ozzy Ozbourn and Black Sabbath.
Really enjoying this thread. Have many of the albums mentioned, and will probably check out a few more. How about some "stuff" for the people that recorded before albums started?
Sister Rosetta Thorpe
John Lee Hooker
Fred Astaire (he first recorded many of the standards still covered today)
Elvis Presley (the Sun recordings)
And some albums:
The Byrds "Sweetheart of the...
Son Volt - "Okemah and the Melody of Riot"
Drive By Truckers - "Southern Rock Opera"
Tab Benoit - "Fever for the Bayou"
Caitlin Cary & Thad Cockrell - 'Begonias"
John Hiatt - "Master of Disaster"
Emmylou Harris - "Brand New Dance"
If you haven't already got it, you might want to try Robert Johnson - The Complete Recordings. He was one of Clapton's, and many other artists, inspirations. I've seen it advertised on the net for $14 to $23. Cheap at twice the price.
Here's a few artists off the top of my head, many have done multiple CD's.
Uncle Tupelo (spawned both Wilco and Son Volt)
Whiskeytown (both Ryan Adams and Caitlin Cary from this group have done solo albums)
You can also check out www.allmusic.com for alt country genre.