How many kids are you planning on inviting? Both boys and girls?
I like Abear's ideas for an outdoor party. If you like themed parties, how about a retro party? This could easily be done outdoors. If you could get a cheap disco ball, that would be great for lighting and for using with the music. Play retro music ( Of course picked out by the BD girl and ONLY if she and her friends like that type of music

).
Have a table decorted with an autograph book and a camera so that when guests arrive, they can sign a quick note to the BD girl and you take their pics. together.
You can decorate with lots of flowers ( flower power

), peace signs and smiley faces. Lots of balloons too.
Seems like retro is the clothing style now ( or at least it was a little while ago--am I still with the times?) Drag out the bell bottoms, clogs, funky shirts and wear braids in your hair.
Pass out peace sign necklaces.
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If you are only having a few kids, A video night party would be fun too.
You could set up your living room like a movie theatre and not spend much to do it.
Rent a couple of movies that she would like to see.
Serve popcorn in buckets, a variety of candy and chocolates and soda to drink.
Later, Serve pizza and you could even set up a nacho bar.
Ice cream cake for dessert.
Create invitations that look like movie tickets.
To decorate, you can purchase movie posters usually pretty cheap from video stores ( some will even give them away)
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Is there something in particular that your daugher is really interested in? We could help to plan a party around that idea too. Just let us know.
Tami