The recycle monster is a good project to do with younger temple members. First you design and build a large container where cans and bottles can be deposited for recycling. Then ask the children to bring in various materials to decorate the container. This can be done with large groups of children (i.e.religious school).
For more information See the Religious Action Center of Reform Judaism's Web site at http://www.rac.org and its publication Lirdof Tzedek: A Guide to Synagogue Social Action at http://rac.org/pubs/saresources/samanual/ and
See the Union for Reform Judaism Department of Jewish Family Concerns material including
Becoming A Kehilat Chesed: Creating and Sustaining a Caring Congregation at http://urj.org/jfc/resources/.