If you wanna do dress up stuff, go to the local thrift stores/goodwill etc and purchase dresses and shoes that you don't care if they get ruined. Plan to have other parents help you do hair, makeup, mani and pedi's then help all the girls get dressed up. Then maybe layout some red isle runner or white whatever you can find and have some fast upbeat music and put a spotlight on the runway and let them have a fashion show while all the parents take pics (flashes going off to add to the show)
another idea is to have each girl bring an outfit they wanna model (helps save money on your end) or several outfits. Have the mom's bring curling irons, hot rollers etc to help get the girls ready. Once ready, continue on with fashion show and maybe give out awards for best walk, best outfit, best smile, best hair etc. Then when show is over let the girls sit around and have cake/ice cream and let the birthday girl open presents. Oh and let the birthday girl be the last one to go at the fashion show with a knockout outfit to go along with her day ;D
Or the other thing is you could do a model photo shoot. Take a white sheet drape it to look like a photo studio and have the girls get all dressed up and have spot lights and fans and let them model for the camera individually or as a group. Those will be some very cute an amazing pictures. What little girl doesn't like to pretend she is a model ;D Hope that helps