There's a very cute one shot called "Mari and Santa," though I don't remember how appropriate the content is. I'm guessing there are a number of other one shots, but no series I know of. Is there a Popotan! manga?
Beneath the Tangles
: Where Manga Meets the Maker
In the colors of Your goodness/In the scars that mark your skin/In the currency of Grace/Is where my song begins
~ "Economy of Mercy," Switchfoot