In the NYTimes 9/2/06 Sunday Arts & Leisure section there's an alright (albeit two years behind) arts& Leisure section cover piece concerning the shift, on the net, to user-controlled and influenced music buying.
One such example proffered, the music genome project at Pandora, allows users to enter in a favorite act and then receive suggestions and sound clips of acts they'd probably also like; this is done to a less exhaustive level on itunes and Amazon. Problem is, if you're a music geek like me, you've already heard most of the suggestions Pandora offers -- but that's only if you start off easy, like I did, entering Guided By Voices and getting slightly wrong suggestions of Superchunk and the horrible Spiders.
Going by specific track makes Pandora seem especially tailored to itunes, to which Pandora links if you want to buy what you hear. Follow the money. Anyone buying albums at Amazon by artists suggested by Pandora, for at least the Dirty Three, will be mislead.
Stumping Pandora is child's play -- enter Sockeye. But that's predictable, Sockeye being a bit of an unfairly obscure choice, legendary as they are for spewing the most offensive and sick punk/sludge/pop in the past 20 years (and no, the Frogs, much as I enjoy them too, aren't as funny or sick).
Yet Pandora should not be stumped by entering Joe Meek. That's embarrassing.
So just email J Frank with bands you like, and he'll suggest others you might like. He might also mislead you intentionally if he feels like messing with you, but then he's more HAL 9000 than he is search engine.