HOW TO – Computer-controlled music-synchronized flashing tree lights
Great holiday Instructable! “Use solid-state relays to blink the lights on your tree in time with music. String lots of lights onto the tree. Use as many sets as you like, but arrange them such that there are three light regions, each with a separate plug. Run these three plugs down the trunk so they can easily be attached to the light controller. Up to three strings of lights can usually be linked in series, so you can almost certainly cover even big trees. Plug light strings into the controller you built for Halloween (MAKE 03). Attach computer and sound system…” Link.
Jamie writes “We had another Halloween party at the Casa this year, and somehow a flash of inspiration hit me when I was thinking about decorations: polystyrene foam balls painted like jack-o-lanterns, on christmas lights.” 
Candy Addict writes “A 
Roland sent along this great DIY site for building Halloween settings “For Halloween 2004, we added a spooky crypt to our graveyard scene. This project requires a fair amount of work, but with a few helpers (at least one of which has some woodworking skills), you too can have a ghost haunt a crypt for your Halloween celebration.” 
Joe writes “So I was sitting around thinking of what our soon-to-be-born kid should be for Halloween this year. I thought that an R2D2 costume would look pretty cute, so I decided to make an iron-on for a onsie. It turned out pretty good, so I want to share it. Print this on an iron-on transfer. Iron it on a onsie. Bam! Cheap baby costume.” 