Sure, Girl Scouts were my life-savers through elementary, and 4-H is EXCELLENT. 4-H actually has programs for all sorts of activities that you might not expect. AND... they have scholarships for college when she's older. Call your local County Extention agent.
Get her involved in Church Youth activities, and help her gather the girls from school that are her friends for activities together like movie dates, trips to the mall, pedi/manicures...etc. Making time for the school friends is really important because, even having friends at church, scouts, 4-H won't fix the feeling of isolation if she doesn't have a friend at school to "hang" with".
Also, I teach. I've taught 11 years of ages 10-12. Girls often come crying to me that "so and so" were mean to me (Yes, pre-teen girls can be NASTY to each other!!)... So, I intervene... then, the next week they are BEST BEST BEST friends. Go Figure! There's an ebb and flow to how they deal with each other. Stay in tune, but make slow careful interventions. Often they work it out.
If it continues, contact the teacher or counselor. They can set up a time for the girls to talk, practice friendship skills...etc. Your daughter will have to deal with these types of issues and people all her life (we as adults know that), So,let her know that it's up to her to decide if she's going to let it bother her or let it go. Can you room-mom for her class? Sometimes the *coolest* kid is the one whose mom is involved. If you can bust up the little kitties and have them spend some time one on one with your daughter, they might decide they LIKE her.