Not too long ago, Homeland Security showed off a new $1 million non-lethal weapon. Billed as the The Dazzler, the device blinds targets with a strong flash, leaving them dizzy and feeling "sea-sick." Since you probably don't have the cool million to spare, you should be able to replicate it in a smaller scale with The Bedazzler, a $250 handheld incapacitator that mimics the effects of the government-issue instrument.
While I'm not sure how effective it would be for temporary immobilization compared to a taser or a heat-generating laser, it should offer a couple more applications beyond the sock-it-to-them-bastards variety. Based on the images, it could work well for use as blinking party lights, as well as mood lighting for some strange-looking photographs.
The Bedazzler is an Arduino-based DIY device that can be set on top of a table or held in hand. Three sets of six LEDs each are used in the sample construction (green/blue lights), although they also recommend using two sets of six LEDs for tri-color displays. The lighting units are housed in a cone-like frame, attached to a single leg, where the power button is placed.
Like the million-dollar weapon it's based from, The Bedazzler is supposed to induce "sea-sick" effects on the poor objects of your aggravation. Nausea, dizziness, eye pain and vomiting are all part of the fun, which means you can use it at work to get the rest of the day off (I doubt your boss would rather keep you in your cubicle while you're throwing up like a blender without a lid). All information on needed components, source codes, schematics and PCB files to build your own are available for download directly from the Lady Ada website (link below).