Lisa Moskow plays the sarod, a 25 stringed lute typical of Northern India. Sitar and tamboura are different.
You could also try the work of Michael Vetter, his "Zen" and "Silence" series of cds are recommended: minimal stuff but highly enjoyable.
On the lighter side, The Moment: they have a couple of cds on Fonix, in which they blend ancient string instruments and singing bowls.
On my own Penumbra, I've released a couple of titles with Klaus Wiese on tamboura, Arpa d'Erba on vocals and me on electronic treatments.