I've seen lots of fun two color quilts lately:
Hunters Star
Irish Chain
Eyes of March (from Quilterscache -- but paper piecing)
Night and Day (eleanor burns)
Depending on the patterns of fabric (if you have fabrics that span the two values), you could also do a Log Cabin with another color as the very middle (red/pink/blue/yellow). I just saw one out here that was gorgeous but don't have a link for you
I just completed one that was mostly black and white and I had originally started out as all B&W, but in the end had to add some pink!