You can throw a party your tomboy will love by letting go of the princess party theme and take her interests to heart. Whether she's outdoorsy or more of a movie buff, zero in on her passions and gear the party toward her favorite things. Regardless of age, she'll want input on the guest list, and don't be surprised if your tomboy expects a co-ed party. Make sure there are lots of snacks on hand and give her room to enjoy her birthday activities with her friends.
Whether in the backyard or on the living room floor, stage a camping birthday for your tomboy. Invite guests to bring their sleeping bags and survival skills.
Set up stations in the yard or in a large indoor space where the girls can practice setting up a tent, tying different knots, making a fishing net, and (if they are old enough and well-supervised) whittling small branches into cooking forks.
They can cook hot dogs over the fire (with adult supervision), make s'mores and tell the scariest ghost stories they know.
Take your tomboy to the video store to select a few of her favorite movies to watch with her friends. Pile pillows on the floor or set up bean bags. String white holiday lights along the edge of the ceiling in the room to look like movie theater pin lights and then turn off the overhead bulbs for viewing.
Offer a movie food buffet of nachos, popcorn, caramel corn and different candies. Suggest on the invitation that party guests bring a DVD or Blu-ray disc as a gift for the birthday girl--this fits the party theme and keeps well-meaning shoppers from buying your tomboy nail polish and lip gloss.
Rent a couple of gaming systems and some games. Set up two gaming stations, one with music-making/dance games and another with racing/sports games. Have prizes for high scorers and a final showdown tournament on each game.
Set up a station in the kitchen for the girls to make their own tacos or pizzas and get a giant cookie instead of a cake so they can munch their birthday dessert while they game.
If you don't want to set up video game systems in your house, hold the party at an arcade with plenty of machines and laser tag.