I just signed up for an account with the new (new to me....recently relaunched) music database Soundflavor. This site not only lets you search for specific songs or artists using genre, lyrics, subject, mood, decade, artist, or album (good for finding out who the hell sings that song you've had in your head since last Thursday...but don't have enough to go on to Google), it also makes new music recommendations based on the songs or artists you find (like a more search-oriented Last.fm).
Each artist page brings together videos, streamable songs, recent news, and similar artists collected from across the web. Disappointingly, I don't think it includes discographies.
If you're into sharing music, or being a good friend, you can build your own playlists or auto-generate recommended playlists to share (or post to your blog...except for Wordpress...lame). Here's a link to my Elliott Smith One-Click playlist (includes music from The Weakerthans, TMBG, and Damien Jurado).
Unlike Last.fm's "similar artist radio," which plays a song once before it disappears into oblivion, the savable playlists of recommended music allow you to catalog and revisit new artists worth digging into.
The next time I need to settle a bet over a song or whip up a genre-driven mixtape, I'm heading to Soundflavor.