I just have no design/color sense. I took the suggestion from one gal and just use the blocks in one long row up and down the length of the BACK of a scrap quilt. Adds some interest to the back and uses them up without having to wrack your brains on things that don't exactly go together. Do a goodle search for Quilt Back Image and you will see a wide array of absolutely gorgeous, but very simply made backs of quilts. It is an awesome collection of hundreds of quilt backs.
The easiest version for me is to take some of the backing fabric and piece the backs into a row with background fabric in between. They look like they are floating along the back.