Buckner International is a ministry that seeks to make life better for orphans, vulnerable children and families around the world. They have published a beautiful advent devotional guide. You may download an electronic copy: http://www.buckner.org/downloads/2010advent.pdf.
December 16 is on page 32. It isn't a prayer guide, but this is an important message about love. What strikes me most as I think about orphans, street kids, abused/neglected/abandoned children is that they have no one to love them. Of course they need safe places to live, clean water, good nutrition, clothes, and education, too.
My first prayer for them is always that someone would find them and love them. I was born into a loving family. I grew up always knowing that I was loved. This is definitely something I took for granted because I never knew any different. What would my life have been like without parents who loved and took care of me?
My second prayer is: what do I need to do to show love to these children? What steps of faith should I take?