I did a search for this here, not finding it, I hope some will find it useful.
I only just now stumbled upon it, so I can't say how 'hit and miss' it is for finding things i want. Hopefully you might add a tune or few.
[www.songkeyfinder.com]

Select notes that sound like they belong in the song

If you like to play along with songs by improvising in the key that they're in, then bookmark this site!

Search our database of songs, or figure it out using the tool above:

Start by having the song playing aloud, then with your guitar start playing notes. Some of them will fit with the song, and others will sound way off. Click on the notes that fit, and when you have narrowed it down enough, it will tell you what key it is. From there try playing other notes in the key, as well as strumming some of the suggested chords.

Have fun,
Shane

PS - my email is below, in case you have any comments - I'd love to hear them