Is there something you believe in?
Saving the whales?
Banning seal cub hunting in northern Canada?
Draft a bill
amnesty international (a letter campaign for the protection of political prisioners, South America, Guantanamo, Iraq, North Korea)
Greenpeace. The recent backdown of the nissu org and sea-lord in new zealand due to letter campaigns is a prime example of how you can change society on a global scale with the power of ink.
Do you believe in bushes war? If not start a letter campaign so we can all bring our boys home, US, UK and OZ boys.
for a 10 week assignment you don't want to send yourself bankrupt, think along the lines of what you can put into it physically and emotionally. You can think globaly or locally.
Are you able to organise a sit-in to bring awareness to some current problem that you see.
Organise activities at your local childrens hospital, you may not save the world but you will change the life of some terminally ill children. We have Canteen in Australia for children suffering with cancer/leukemia. It is a camp where they attend to have a break form their illness with other children.
Ronald Mcdonald house, fund raising. Put together a well planned proposition to large companies known for their social responibility, could be to support a local charity, mission.
organise collections in your area, a drive. Your local red cross may have some things going on. I'm assuming your in the States and being in Oz, myself i'm not exactly sure of what charities or missions you have. St Vincent De Paul are a fantastic society for homeless and poor.