Some other ideas:
1. Get some friends, pool your $100 contributions, buy cleaning supplies and paint and tools. Go to homes of seniors who need assistance and clean, paint and fix whatever their home needs.
2. Buy some art supplies (paint, canvass, sculpting clay, etc) and meet weekly with underprivileged children to create.
3. Host a film fest in your home or apartment complex. The $100 goes to renting movies, or maybe a projector for outside viewing (weather dependent) and providing snack foods. Then, discuss each film, teasing out themes that relate to the Kingdom.
Blogger challenge-- post the link and come up with your own ideas. Spread the word.