There's a Mancini Plus One book for alto that has Pink Panther, Peter Gunn,
Slow Hot Wind, amongst others, with backing tracks on the accompanying
CD.
If you haven't done this already, I recommend that you follow Jamey
Aebersold's advice and learn Happy Birthday, Twinkle Twinkle/ABC, and songs
like that. Play them by ear (no sheet) in a comfortable key, and then take
each one around all twelve. If you do that for twenty or so tunes you'll start
getting the hang of playing things by ear. If I could only practice one thing,
playing songs I know by ear from memory would be it.