I keep a box of scrap squares by my machine to use as leaders and enders....usually make either 4-patches or 9 patches. After awhile, when I have lots of blocks, I will put them together into a quilt. Some of my favorite quilts have come from these blocks. It is a way to sew 2 quilts at a time without really thinking about the second quilt...just doing them inbetween the other piecing. The Quiltville site has a great explanation and lots of scrap quilt possibilities!