As an unashamed member of The Cult of Buffy (1996 - present), I have of course tracked down a copy of "Radio Sunnydale" (finally).
I am ecstatic to report that this album is a glittering treasure trove of obscure US indie artists. The only band I have ever heard of is The Dandy Warhols (not that they're obscure, but they're the only ones on the album who aren't, in the UK at least). This is an album to give your full undivided attention to - stick it on your ipod and listen to a few songs at a time, would be my recommendation. I have no idea who Devics are or were, or indeed Dashboard Prophets, Lunatic Calm, or Nikka Costa, but I would certainly like to find out more about all of them.
In terms of musical genres the album varies, but it's fair to say that it all pretty much has that bittersweet "life would be so beautiful if we weren't all completely doomed" kind of vibe that runs through the tv show from start to finish. Which is wonderful, in my book. I love this album. When eventually I have sucked out every drop of goodness from it, I'll move on to buying up albums by the individual artists. Mwahahaha!
p.s Incidentally, the only song I actually remembered hearing from an episode was "Sugar Water" by Cibo Matto, which is the background music to Buffy giving Xander a bit of a sexy dance in Season 2 (I think).