Take a look at Bonnie hunter's site. She has a scrap system, with sizes to cut an scores of free patterns
http://quiltville.com/scrapusersystem.shtml
Patterns
http://quiltville.blogspot.com/p/free-patterns.html
at the top of the pattern page, she has a chart that lists what sizes are used with what patterns so if you get a bunch cut of a particular size, you can go right to the patterns that use them.