My Daughter's Turning 13 - San Jose,CA

My youngest is 13. The two ideas she came up with when I asked her this question were a Minute to Win It party (this is what she is planning for her 14th in Feb.) or the photo safari party we did for her sister a few years back.
Minute to Win It is a sort of game show where the contestants have to accomplish some crazy thing in less than a minute. I think you can youtube some good ideas for that one.
The photo safari requires a non-rainy day, so it depends on when her b-day is. Can you count on a dry day? If so, this is what we did. We broke the kids up into teams of 3 or 4 and gave each team a digital camera (we have one, and we borrowed the other 3 from friends). We explained the boundaries of the safari (certain streets to create roughly a square area) and gave each team a list of 13 things to find (a house with the Christmas lights still up, an awesome car, an ugly old car, a dog, an animal not a cat or dog, a pretty garden, a house in need of a paint job, etc.) the list included two 'most' categories, most basketball hoops and most signs ( any kind of hoop or sign, but only one picture of each one you find. No duplicates) They had to have at least one member of their team in the photo and presentation counts! We gave them about an hour and a half to find everything on the list and get back to the house. When they returned we dished the cake and ice cream and then plugged the cameras, one by one, into the tv to view the photos. Some of the pictures were hilarious! Some were very artistic and creative. We had four teams and all the kids agreed on the overall winner. This was a few years ago and the kids still talk about it. It combined creativity and independence, but still was age appropriate.
Have fun!

sporting events always bring kids back down to earth as far as their age and ability are concerned. bowling? skating? tennis?

Bowling is always fun. I have 2 teenage daughters and they both really enjoy it. Some of the newer bowling alleys like 300 are really nice and the food and music is great too!

A special "girls day out" maybe?
Manicure, pedicure, hair cut and/or styling.
Out for dinner somewhere (relatively) sophisticated w/mom and dad,
maybe w/grandparents if they're close by.

A PG-13 movie and lunch.
A trip to the mall and lunch at a restaurant.
Have the get manicures and pedicures together.
Shopping is always fun!

L., first off let me say take 2 asprin and hope for the best as 13 was a rough year for both my girls... I became the world's dumbest mom and didn't get smart again until they were 18! As the mother of 5 I am thankful for the boys who go thru it in an entirely different way.
As for the party. I have held several "Tea Parties" for young ladies.
I have collected many fancy tea cups and really cute teapots. We served herb tea, hot coco, and lemonaid. I made traditonal sandwhiches and small desserts. Decorated the tables very ladylike and then had the girls come dressed for a High Tea. I used the old fashioned glass plates with theglass cups, and had someone demonstrate how to clean silver, the art of conversation and how to pour tea properly. The girls have had a ball and they really got a blast out of dressing up . The hoot was when a girl said she has never seen her mother use china, or fancy tableware-- they use fancy paperplates for special dinners! This gives the girls a chance to practice something they may need in the future and learn some old fashioned skills of talking to one another. Bet you could borrow tea pots. I have gone to thrift stores and consignment stores for the tea cups and then give them to each young lasy to take home as a gift. You can look online for ideas. Have fun and good luck this next year.