Someone just posted this pic
http://www.quiltingboard.com/t-146258-1.htm
It got me thinking that you could maybe do something like a bargello type quilt with your rectangles, or even a Trip Around the World (or Mini TATW) pattern.
Instead of the usual use of a few fabrics, you could build it based on a gradiation by sorting your rectangles by value, regardless of color.
Too bad they aren't all 2"x3.5" - a lot more flexible.