Yahoo has a beta of a new audio file search service. They’re indexing songs available from many online music services, including not only iTunes, Napster, etc, but also Audio Lunchbox and other web sites (there’s a list of services indexed ).
Using it turns up that Musicmatch has the Jethro Tull album I was looking for the other day.
Searching “Whispering Johnson” does indeed turn up my own band’s tunes (though not first on the list).
It seems to me that aggregator services such as these should, in the long run, increase pressure to distribute music in standard formats.