This Year I was bound and determined to make something that would stand out.
An LED battery operated set of lights cut up and hooked to an Arduino, Charlieplexed style, and a little code to make them bllnk in nice patterns, changed randomly, filled the bill.
It took some time to get the random part to work, but I didn't want the pattern to repeat over and over and get boring.
I could have fancied it up hiding all the connections and putting the arduino in an Altoids tin. But I wanted them to see all the wires. Besides, its geekier that way.
Step 1: Finding the Positive Side of the LED
I cut them apart then used the supplied battery case to find the positive wire for each.