Here's another link to a recent article on my web site. It is part of a series of TABs for playing the descending versions of the three most important modes on the dulcimer (the dorian, the aeolian, and the mixolydian):
Descending B Aeolian Mode in DAD Tuning
This version uses as much of the drone-notes (B and F#) as possible in supporting the descending melody. There are also many ways of harmonizing the mode with chords: I like to restrict these to the basic triads of each mode, and maybe a substitute triad now and again. The main substitute triad for each of these modes is the subtonic VII (sometimes written bVII) to substitute for the minor V chord (sometimes written v):
E Dorian: Em - A - Bm (D)
B Aeolian: Bm - Em - F#m (A)
A Mixolydian: A - D - Em (G)
...where the chord in parentheses is the VII or bVii subtonic.