My DGD (4-1/2) loves to work with fabric and uses my Janome. Our deal for now is she can either run the foot pedal, or feed the fabric through the machine, but not both at the same time, so I get to 'help' her with her projects. Once she's got a little more control of both we can change the arrangement.
Great thread, everyone has such good suggestions! I think this little girl of mine needs a machine for her next birthday....