My Make: Books co-conspirator Brian Jepson has posted a quick n’ dirty way of building a 64-node LED matrix (green and red, natch) of holiday lights, driven by a Max 7219 chip and controlled by an Arduino cloneboard. Not too shabby. The resulting LED “net” will only cover a small tree. For a larger tree, you’d have to do a much more ambitious build and cascade Max chips, but it seems to be time-consuming than anything else. Being the geek that he is, Brian also got the thing talking to his mobile phone over Bluetooth, which he promises more info on soon.