I love the "Nana's Boutique" idea!
I have boxes with the kids names on them, and when they come over (one kid every other Sunday afternoon), we continue a project that we have been working on. The oldest girl (almost 12) is making a patriotic log cabin throw for her great-grandma. The oldest boy (almost 13) is also working on a quilt, but I cannot remember what it is at the moment (good thing the box is marked with his name!). The younger ones haven't got any long term projects going at the moment, but we always work on something!