A Season of Hope
One of the best is the Advent calendar at the Diocese of Washington, which comes online today. It has good resources to assist children in learning about Advent, with links to images at the National Cathedral.
For a refresher on Advent and for those wondering what it all means, The Christian Season of Advent provides a fine statement along with other information.
Advent also symbolizes the spiritual journey of individuals and a congregation, as they affirm that Christ has come, that He is present in the world today, and that He will come again in power. That acknowledgment provides a basis for Kingdom ethics, for holy living arising from a profound sense that we live "between the times" and are called to be faithful stewards of what is entrusted to us as God’s people. So, as the church celebrates God’s inbreaking into history in the Incarnation, and anticipates a future consummation to that history for which "all creation is groaning awaiting its redemption," it also confesses its own responsibility as a people commissioned to "love the Lord your God with all your heart" and to "love your neighbor as yourself."