Have a henna stand for designs that move beyond the confines of the fabric. Henna can be purchased at any Indian or international specialty grocery store. Get a creative friend to help with the application as it can be messy and henna permanently stains skin for about two weeks, depending on how long the henna paint is left on the body.
Working with the same theme of creativity and inspiration you could set up a face painting station. Grab face paint from any arts and crafts store, a variety of brushes for your guests, as well as fun favorites like applicable gems and glitter. You can either have an adult run the station and apply face paint or let the kids go wild with their own designs (with adult supervision of course!).