Some unknown genius (possibly redditor Tmyakal) created this insanely great Portal-themed Christmas Tree that presents the illusion of a tree being shoved through one of the interdimensional portals in the kick ass Valve game.
Update: Ryan Kelly sez, "I'm a big fan and can't tell you what a great Christmas present it was to see our Portal themed Christmas tree posted on Boing Boing. It was done by myself and my two business partners as a nice, stress-relieving break from working on a film we are making and was posted by a friend of ours on Reddit."
Basically, it's our artificial tree which comes apart in three sections. The top section is suspended from the ceiling by an adhesive hook so it simply hangs downwards. The other two sections are connected and placed upside down on the floor - the tricky part is that the branches are meant to be kept extended out by gravity, so there is fishing line attached between each branch and what is usually the base of the tree, pulling the branches up towards the ceiling.
We then got two sets of rope lights (blue and red as we couldn't find orange). We laid the red out in a tight circle around the tree on the floor. The blue was wrapped in a circle, scotch taped to hold together, and then hung on to more adhesive hooks on the ceiling. Then we cut two circles of black poster board and placed these beneath the rope light rings to give them the feeling of holes. You barely see the black with all the branches and the portals lit up so it plays fairly well.
Finally, the hanging top piece didn't have branches that extended all the way up to the ceiling, so to cover the obvious gap we bought some artificial garland and wrapped that around it to match up with the ceiling. That way it looks like the tree continues up into the surface.
With a little bit of finessing, you can hide any of the obvious gaps and have one seamless tree.