My 11yo just went to a birthday party...they went swimming (still hot here), painted each other's nails, and tie-dyed t-shirts. I think the make-up/pampering thing is a good idea if it's ok w/the mother. My 11yo doesn't get to wear any cosmetics except lip gloss out in public, but she LOVES to experiment w/eye makeup, blush, lipstick, etc., whenever she gets the chance. Something 'crafty' also often goes over well. The tie-dye was a big hit, but other ideas might be decorating notebooks/journals, pillowcases, aprons, handbags, picture frames, etc....something that they can use again.