If you are looking for larger quilts,
www.country-schoolhouse.com (who created the rulers) has 2 books out. If you want some fun wall hangings or baby quilts:
www.marthadzines.com,
www.handcraftsbyjennifer.com, and
www.gatheringroomquiltshop.com all have different shaped Twisters. I'm sure there are other sites, but those are the ones I know most people like.