I'm looking for music for my duet (flute & alto saxophone), but there is not a whole lot of music written for alto saxophone and even less for a duet. In terms of range and technique, what are some other instrumental parts that the alto can play? Double stops are okay.
I am playing tenor, but both me and my teacher thought the scores in Kevin Mayhew's "Tunes for Two" were more suitable for alto and flute, so you might find that book good enough for your needs if you don't mind classical music and if your flute accompaniment is good at transposing on the fly. We've played them with my teacher playing tenor and me playing soprano as well in the past, and it turned out alright.
If this doesn't answer your question, let me know, and I will shoot an email to my teacher: he's a flute player as well, so he might have a better idea as to what might be more suitable.
Here's what a Google search yielded:
Another thing you could do is have Guitar Pro installed (or Sibelius, or any other notation program that supports ASCII tab or MIDI import and allows printing/exporting to PDF), import tabs or MIDI files and then transpose them to your heart's content. There's tons of music sheets transcribed to Guitar Pro tabs and MIDI format around the Internet.