Take your group on a mission trip together. These can often be done through an organization and require very little preparation, but may need some funding to get your group there.
Have your group commit to saving their extra change throughout the season of Lent and donating it through the Rice Bowl. They could commit to doing it personally or you have a Rice Bowl at [...]
Get together with a couple other groups and do a free car wash in the Church parking lot. That's right, don't charge a dime. Instead make flyers or cards that thank them for stopping by [...]