It's trivially easy to build a taser out of a disposable camera - the power source for the flash is the key component. However, you are likely to end up with a device that is a lot more lethal.
http://www.ehow.com/how_2049857_tase...le-camera.html
The flip-side of frequent taser use is that people are going to start figuring out how to protect themselves. It doesn't take much, just a conductive layer of clothing. As long as both eletrodes touch the conductive layer, the electricity won't enter the person's body - even if the darts are also embedded in the person's skin.
There is already a company selling clothing with a layer of conductive polyester embedded. They look just like regular street clothes. They even have a video of a guy getting tasered in various ways without any side-effects (for example, they've got a baseball cap with the material in it and they put a taser directly to the guy's head in 'drive-stun' mode and nothing happens to him). They call it Thor Shield.