I s'pose you could use them to mic in stereo, though I have other mics for that. And they could be used as an overhead AND a tom mic on your drums, or even as a pedal mic, though there are plenty of better choices.
I believe, in the killer mic thread, Harvey even recommended a pair of 57's for Leslie miking, plus a 421 for the bass rotor.
BTW, I have two, plus a 58.