Add inaccuracy to a raycast

I am working on a script for a FPS, and im trying to add a slight random inaccuracy to a raycast. So it casts the raycast forward, but it diverges by a random amount of degrees from the absolute forward.

Anyone have a suggestion on how to best achieve this?

Check the top answer that was posted here:

http://answers.unity3d.com/questions/5602/fps-gun-accuracy-bullet-tracers