Since everyone else is posting rock, metal, and progressive, I'll vary it a bit with some Ecto bands (I will add a few of the aformentioned though ;D )
I'll post links to band info elsewhere if some other page explains enough.
The Jazz Mandolin Project Splashdown: I'm really into some of the songs made by Splashdown. Something interesting is that when the band broke up, they made their music free to share online, even their unreleased album blueshift. Almost all of their songs can be downloaded
here. Their music varies, so one or two songs don't reveal how different the band can be at times. Also, if anyone's played Amplitude for the PS2, Melissa Kaplan (the band's singer) offered her vocal talent for "Shades of Blue" in the game.
Kyuss: A song I highly recommend by them is Demon Cleaner.
Threat Signal: Pretty good metal band.
Fear Factory: Pretty GREAT metal band. Their songs tend to be in three different styles, depending on the album usually. There's a hardcore (and their original) approach to metal, remixes that they do of their own songs every now and then, and then they have an awesome combination of the hardcore style with emphasized vocals, which changes it a lot. For the first style, I'd recommend H-K (Hunter-Killer) from their album Demanufacture. For the second (which is my least favorite, to be honest), try Genetic Blueprint from their remix album of Demanufacture, titled Remanufacture. And for the third style (definitely my favorite), the vast majority of their new album Transgression will do, but I highly recommend Supernova and Moment of Impact.
Refused: Fantastic hardcore punk band. The album I'd recommend from them is without a doubt, The Shape of Punk to Come[/url]
The Dandy Warhols: Very interesting band. Claimed to be rock, but sort of different from traditional rock I'd say. Worth checking out. The styles in their various albums vary greatly, one or two songs of their are available on their
myspace.
I'll post more some other time.