Maggie Latham has some interesting posts right now on her blog - she's sharing how she uses inks with watercolor: not in the traditional way of using the ink as a drawing tool and then coloring in with watercolors, but using the inks as watercolor.
Get out your India Ink and brushes and try it. I actually accomplished a couple paintings this way that I like! They are both small studies (7.5" x 11"). I put down the ink first on damp paper in No. 1 and then washes of Azo Yellow + Prussian Blue. In No. 2, I put down the ink after the watercolor washes.