Thank you for this superlative resource...
...and also for the link to kachingle, of which I'd previously not heard. Looks promising.
If it's helpful for you to know this, and you don't already, found you via a writeup here:
http://mashable.com/2010/03/30/identify-song-apps/
which in turn came up 3rd listing, 1st page of a Google search for:
music identifier online
the same search that showed your site directly in position 40 (bottom of 4th page at 10 results / pg).
As my post-headline indicates, I was hoping that there was a feature that I've somehow overlooked, allowing one to save searches that don't come up with the sought tune, in the expectation that, as the database expands, previously un-found tunes might eventually manifest.
I'll come back to check sooner or later anyway, but if there is already such a feature that I've just not yet been able to find, I'd love it if someone wanted to alert me to this by e-mail:
[email protected]