She has only been there one day. Remind her that middle school really is hard for most of the kids, it is just that some of them are good at hiding their fear.
Do you all have a back to school night? You could find out what clubs are available there. Also what is she taking for electives? Maybe if she is taking art for example you could find out if they have an art club for her to join.. Spanish club (ours takes a trip to Spain each year)..
Has she ever taken the First Aid babysitters training through the Red Cross? If not, see if you can organize them to go to your daughters middle school one Sat and train a bunch of the kids..(boys and girls) They usually have to partner up, so she would be in a smaller group and get to meet friends..
For the dances, at our middle school they had a group of kids that helped decorate the walls and set up and run the Karaoke area.. Some of the kids helped sell snacks..
At the local elementary school Carnivals they always had kids from the middle school help run their booths.. Your daughter could gather names and organize a group.. This would count towards Volunteer hours.
In the Library they had a "Lunch Bunch" that would meet in there and work on jigsaw puzzles. They also had a group that met each lunch to play chess..
Find out how to work on the school newspaper, yearbook. Get her a camera and let her be the historian for the paper and the yearbook..
Maybe the Librarian will know if there is a book club at school she would join.. Maybe she could start one?
I know this is hard for you, but she will be fine, she just needs to find a little group of nice kids with similar interests.. They are there too looking for a friend.. she jsut needs to look around and find things she is interested in.