I spend "fun" days with my nine yr old niece sometimes and she loves to paint her nails so I always go to walgreens and pick up 99cent nail polish is out there colors before she comes and then we spend time painting her nails. Sometimes she will paint all her nails different colors or I help her do polkadots or stripes. Because of drying time and doing nails and tonails it can take up a lot of time. Also go to doller tree and pick up some hair ties and a pack of combs and the girls can do eachotheres hair.

Stock up on the wine...YOU'LL need it!

For my SD's birthday slumber party I had the girls make magnets. I painted a section of SD's wall with magnetic paint (her birthday present was a redecorated/painted room). I bought a bunch of colored foam sheets, glitter, foam sticky letters, magnets, etc. that the girls used to create custom magnets for my SD's wall. And, each of them made one for their moms and one to take home as a souvenir. It kept them busy all night.

Get pipe cleaner and do this...http://www.haveafunkyhairday.com/index.html They do it at the street fairs and the kids love it.

When my girls were this age they got quite excited at parties, and you might need some physical activities to work this off - I would suggest things like musical statues, where they can dance while the music is going and when you stop it, the person last to keep still is "out" - that person then takes their turn to watch for the next.
If you have a reasonable size house or garden you could do a treasure hunt, with about 15 clues written on slips of paper leading to the next clue, and a small prize at the end - I used to get the girls to do this in pairs.
Also in pairs, they have to transform their partner into a "mummy" with a roll of toilet paper, again , a small prize for the best.

We also did a "makeover" party. I bought a buncha dollar makeup - and let them have at it, doing a "before/after" picture. The girls thought it HYSTERICAL. Lipstick on they eyelids, blue lips, green cheeks, they thoguth they were fabulous (and probably were channeling a much younger Gaga).

the photos are now all on facebook. One of the girls is getting ready to graduate high school, and she has tagged herself and made that photo her profile picture.

Also, I had them write out a letter to themselves for a year later. I kept them all and then mailed them out on my daughter's next birthday. some had moved, but if there was a forwarding addy - it went to them.

We did a nail polish game where you spun the bottle of nail polish, and whoever it pointed at had to paint a nail that color. It was a good way to keep the little girls engaged.

Also, we used fabric paint and painted pillow cases.

Dance party, and we ended the night watching a movie (turned down low) so that they had to be quiet to hear it.