Support the Peter's Pence Collection in your parish.
If you miss the collection, or your (arch)diocese does not participate, you can send your donation to:

Peter’s Pence Collection
The Apostolic Nunciature
3339 Massachusetts Ave., NW
Washington, DC 20008

Make your check or money order payable to "Peter's Pence Collection" 

The Holy See can receive donations directly at www.peterspence.va.