A dynamic fracture system that can be readily used with Unity cubes only, if you want to shatter other meshes then the PRO version is for you.
This system uses a voronoi algorithm to dynamically fracture objects at runtime. These fractured pieces (or shards) give the impression that objects have been destroyed.
This tool is the first part of a much bigger system, and it's modular design enables it work standalone, or together with the rest of the destruction suite.
Check out this webplayer demo
NOTE : This version doesn't come with the source code. (See pro version).