More than 500000 children are underway as "star singers" (Sternsinger) at this time of year (predominantly today, January 6, Epiphany) in the German-speaking nations of Europe, i.e. not only (but predominantly) in Germany, as also in Austria and Switzerland.
Epiphany as a Christian religious feast most certainly first marked the nativity or baptism of Christ, although the tradition may go back to even more ancient astronomical celebrations.
The star singers are sponsored by the local Catholic churches and this year in Germany are underway under the motto "Sternsinger für die Eine Welt" (star singers for one world).
The star singers ring doorbells at households all across the land (primarily in Catholic areas), and when those doors are opened - it is considered bad luck to send the star singers away without opening doors for them - the star singers then sing songs of faith at those doorsteps in order by collection to raise money for needy children around the world. Below are some photos of the star singers:
A 2004 AP photo from Deutsche Welle
A photo of star singers in 2007 at the doorstep of the Parliament
of North Rhine-Westphalia, Germany's most populous State
A blessing is written in chalk by the star singers on the front door of the household, marking the current year, together with the initials of the three Biblical kings (or wise men):
See the blessing to the left, wirtten in chalk on a door this year 2008.
It is also possible in the course of development of this custom that the initials CMB - always in that order - either initially or subsequently meant Christus mansionem benedicat, which translates generally as "may Christ bless this house".