I'm currently working through an ongoing mystery quilt from a guild somewhere in NY but I don't attend that guild but it's quite easy.
http://quiltschenectady.org/?page_id=851
that's the current mystery but they have a few other mystery quilts there as well. You could also check out Bonnie Hunter's mystery quilts, they look like fun too and I might do double delight, if I don't peak at the last clue :P