Some Alternatives
Just a little plug for the Girl Scouts here (my employer).
Girl Scouts is a great organization that is doing a lot for girls, and a good part of the funding is from cookies (for the girls, their troops, their Councils, and the costs associated with running a national organization). GS has many programs nationwide that promote health and fitness activities for girls. In addition to programs and badges/patches, we host a 5K/1K walk/run here in Denver, and I direct a resident camp that has backpacking, horseback riding, rock climbing, archery, and hiking. All these cool activities are offered far below cost due to subsidies, the largest of which is often cookie sales.
Want to support Girl Scouts but don't want to eat cookies? Here's how:
Make a donation straight to the troop or your local Girl Scout Council for the amount you usually spend on cookies.
Buy boxes of cookies from your door-to-door Girl Scout for "Hometown Heroes." Most troops sell extra boxes of cookies that you can 'buy' and have given to firefighters, police officers, or military that the girls have selected as their "Hometown Heroes." Buy cookies, support the heroes, and no calories consumed!
Volunteer at your local Girl Scouts. You don't have to make a long-term commitment (i.e. as a troop leader) to make a difference in the lives of these girls. Call your local Council's volunteer coordinator (use the "Council Finder" function at
http://www.girlscouts.org), and offer to organize a running club, teach a step class or talk about the fitness lifestyle to girls at a troop or Council event.
My personal favorites are the peanut butter patties called Tagalongs (a term applied to little girls or boys that "tag-a-long" with their volunteering parent at day camp or troop activities) and the new low-fat Lemon Coolers (much better than their Ole Ole predecessors).

Gretchen
Girl Scouts -- Mile Hi Council
"Where Girls Grow Strong"