For those of you unaware, there has for several years been a tradition of exchanging conlang & conculture related greeting cards around this time of year among folks of various conlanging communities. I couldn't find any reference to previous exchanges here in CBB, so will let this stand as both open invitation and explanation.
First, what it is: basically, you make (and make copies of!) a greeting card in your conlang -- it can be a primary world oriented card with your message written in your conlang, or it can be an actual artifact from your otherworld. You'll register (starting Friday, so they say) your name and physical address (any address you can get actual mail -- home, office, school, PO Box, APO, etc). Then you'll get a list of participants' addresses and you'll send your card to however many folks on the list you want to send to.
In the past, people have sent commercial Christmas cards with greetings written in their conlangs, others have sent purely concultural items, some have sent short notes. Hand made, computer generated, does not matter.
Folks from anywhere in the world are welcome to join the fun, and the more the merrier!
Check out the official page here. The galleries are out of date now, but anyway, you can get more details there.