I just finished reading Night Circus by Erin Morgenstern (yes, I'm well on my way to reading more than my usual number of books intended for adults this year). One of the circus tents in the story features a Wishing Tree: "You take a candle from the box at the entrance and light it from one that already burns on the tree. Your wish is ignited by someone else's wish." Charming concept, no?
The image reminded me of Yoko Ono's Wish Trees, which were inspired by her childhood memory of writing a wish on a piece of paper and tying it around a tree branch at a temple in Japan. Wish trees appear in various forms in other cultures around the globe, as well.
If you're still trying to devise a way to participate in the Magic Mission, I believe creating a Wish Tree for your community is another lovely* option. Igniting some hopefulness in this world fits the purpose of the project perfectly. :)
*and simple! All you need is paper, a hole punch, yarn or string, some writing utensils, and wishes! Oh, and a tree, of course.