13 awesome postage free ideas can be found here on the Desiring God site.
Please know that I'm NOT asking for any of these!! I am simply passing on some great ideas that I know would bless the missionaries in your life. :)
I specifically recommend the ones that do not cost a penny at all:
- Commit to pray for them on a specific day of the week for a year.
- Write a song or poem or story for them. Email them the text and a recording of you reading or singing it.
- Get friends and family together to create a holiday video greeting for them using Google Video or YouTube. Include lots of people you know they miss.
- Pray specific Scripture for them and their ministry, and then email it to them.
- Call or email their parents—Christmas might be just as lonely for the ones at home as the ones away.
- Donate frequent flier miles to them. (I don't know this one might cost you a penny or two, but would be a great idea if you know what airline they already have frequent flier miles with or if you have enough for an entire free trip. I know of several missionaries who have flown to the field or gone home during crises by "paying" for tickets this way.)