This one is a holiday in only three of the German states, and I'm lucky enough to live in one of them: It's January 6th, or 'Three Kings Day'. I did a bit of research again (wikipedia, my love), and learnt that actually, the day is called 'Epiphany' and celebrates the revelation of "God the Son as a human beeing in Jesus Christ". In our tradition, this is marked by the visit of the Magi, the three Wise Men or the Three Kings, as they are mostly called here. I also learned that the holiday goes back quite a while: Epiphanie and Christ's birth used to be celebrated together on this date, before the Roman Catholic church changed christmas to the 25th of December in the 5th centuary. Apparently, some parts of Christianity still celebrate Christmas on the 6th of January. But even before that, the 6th of January was an important holiday in Ptolemaic Egypt and Rome.
In Germany, or at least where I live, Three Kings Day isn't a holiday in the sense that people celebrate it themselves - it's a day off work though. Nativity scenes at home or in churches get an addition of the three wise men (when we had one when I was younger, they were already there on christmas eve, but at the far edge of the scene, not in the stable itself, and got moved a bit closer to the actual crib every day). There are also the Sternsinger (star singers) - groups of children dressed as the three wise men (though there are not necessaryly three, and girls are allowed as well). As they are known as the three kings Caspar, Melchior and Balthasar around here, and Caspar is usually depicted as dark-skinned, at least one of the children usually has it's face painted black or brown (I bet that's considered racist now as well...). Those star singers move through the streets, stoping at every door to sing. They collect money for charity (usually for other children) and if you give them something, you get a blessing on your doorframe: 20*C+M+B+15 (2015 for the year, the star for the star of Bethlehem, three crosses for the holy trinity, and the initals of the Three Kings).
The star singers are organized by the Catholic church, so I was never part of them when I was younger, though I always wanted to. Nowadays, less and less children are interested in joining them, so they are more open now. There still aren't enough to cover ever house anymore, especially in cities - they used to walk aorund all week instead of just January 6th, but now they will only come if you send them an email beforehand. I think that's pretty sad, it's a great tradition and they have been doing a lot of good with their collecting - in 2005 alone, they got about 47 millions!