Here's a list: tuba, bass guitar, saxophone, clarinet, trombone, trumpet, flute, piano, percussion, oboe (not the best), recorder, and baritone/euphonium. Most of which are band instruments (well, almost all are).
I don't get to play with guitarists much aside from the church group I'm in on my bass. Usually when they give me chords to song, I improvise a bass line of sorts. I usually get really intricate with it since I understand theory and such. I'll tell you one thing on bass that works it to learn what are called neighbor tones to certain notes (notes that, when played in a scale, are on either side of the note) and use those to lead up or down to whatever note you're going to (say-C, NT's are D and B). Make sense? Sort of?