Basically, recommend to your fellow forum-goers bands & other music artists you feel don't get enough love and exposure here. This is not limited to any era or genre, though I'd like to see recs not solely limited to prog.
Antimatter (Ambient Progressive Rock) - Fans of Anathema will be familiar with these guys. They're very mellow, melancholic and atmospheric.
Astronautalis (Indie Rock/Hip Hop) - This guy is incredibly unique and I insist that anyone intrigued by the genre description I gave him check out his album Pomegranate. Rec. songs: The Wondersmith and His Sons, Two Years Before The Mast, Trouble Hunters, The Story of My Life
Atmosphere (Hip Hop) - One of my favorite groups in hip hop. Check out When Life Gives You Lemons, You Paint That Shit Gold and God Loves Ugly.
Blue Sky Black Death (Instrumental Hip Hop) - Basically hip hop without rapping, focusing on atmospheric beats and samples. Check out their album Late Night Cinema.
Children of Nova (Progressive Rock) - They may come off to some people as a less insane clone of The Mars Volta, but they're still quite good. Listen to their songs Arcaedion and The Complexity Of Light.
Cire (Alternative Rock/Progressive) - Exactly what it says on the tin: intelligent alt. rock with a progressive edge. Listen to Red Queen and Adrenological.
Closure In Moscow (Progressive Rock/Post-Hardcore) - Somewhat of a more poppy version of The Mars Volta, though not something I see appealing to this forum. Still, Vanguard is a great song.
Cloud Cult (Experimental Indie Rock) - I only have their latest release, Light Chasers, but it's nothing short of a masterpiece. Give it a listen.
CunninLynguists (Hip Hop) - One of the most brilliant and consistent groups in hip hop. Listen to their albums A Piece of Strange and Southernunderground and check out the songs Nothing to Give, Beautiful Girl, and The Gates (Feat. Tonedeff).
Dr. Steel (Steampunk-flavored industrial/opera-rock/hip hop) - Intrigued by what I put as his genre? You better be. Imagine if Mike Patton, Danny Elfman and Peewee Herman had a threesome and gave their child to a mad scientist to raise and you have Dr. Steel. Listen to Planet X Marks the Spot, Lament Of A Toy Factory, Fibonacci Sequence, and Childhood (Don't) a Go-Go. Help this man take over the world.
Elliott Smith (Acoustic/Singer-songwriter/Indie) - The late Elliott Smith was actually quite well-known, though not someone that would appeal to many here. However, he's one of my favorite artists, so I'm throwing him on this list for good measure.
Fair to Midland (Experimental Alt. Metal) - Alternative rock with a bit of a progressive/folk edge. Listen to Dance Of The Manatee, April Fools and Eggmen and Tall Tales Taste Like Sour Grapes.
Flying Lotus (Electronic/Instrumental Hip Hop) - Not sure what to say, so I'll leave it at this: check out his album Cosmogramma, it's one of the best of 2010.
Hurt (Alternative Rock) - Incredibly solid rock with some metal & progressive elements. Check out Vol. II and the songs Summers Lost, Rapture, Overdose, Thank You For Listening and Wars.
Immortal Technique (Hip Hop) - My absolute favorite artist in hip hop, listen to Dance With the Devil, The Point Of No Return, Leaving the Past and Revolutionary.
Jeff Buckley (Singer-songwriter/Rock) - The entire world should know of the great Jeff Buckley, but sadly, they don't. Do yourself a favor and listen to his album Grace.
Opus Däi (Progressive Metal) - Nothing original, but extremely good at what they do. Listen to the song The Day The World Stopped Turning.
Parades (Experimental Indie Pop) - A new band that just came out this year, their debut album Foreign Tapes is one of my favorites of the year thus far.
P.O.S. (Hip Hop) - Any fan of hip hop needs to go listen to Let It Rattle, Purexed, Goodbye and Half-Cocked Concepts. Right now.
Rob Dougan - I don't even know what to put as his genre, so let last.fm explain: "Rob Dougan is a genre-blending music composer. Mixing the sound of orchestral film music, the beats of club Trip Hop, and bluesy vocals, he is only tangentially relatable to electronic music." Now go listen to his one album Furious Angels, it's one of my favorites.
Streetlight Manifesto (Ska Punk) - The most fun band in my entire music library. Those not turned off by the genre should listen to Everything Goes Numb.
Thomas Dybdahl - A Norwegian acoustic singer-songwriter, listen to Something Real, From Grace, Cecilia, and one day you'll dance for me new york city.
Tom Waits (Experimental Blues Rock) - This man recently overtook Pain of Salvation as my all-time favorite artist in music. He is not someone I think the vast majority of DTF will find appealing or even good, but regardless, I can't leave him off of here. Go down the rabbit hole and listen to the albums Rain Dogs, Bone Machine, Alice and Swordfishtrombone.