1. "Ball" has core of C4, surrounded by wire, etc. (i.e. it's a grenade with a bigger bang)
2. Add increased range.
3. Add ability to "bounce" (for stairs, etc)
4. Add firing mechanism.
You now have a movable, controllable grenade. Ideal use: Room clearance. Turn ball on, roll into target room, bounce to waist height, activate.
You could easily modify this with CS gas or such for lower lethality options.
You could have them roll back to a base point for self-charging. To make them airborne you could embed the standard model in a quad-rotor "collar" and use the rolling mechanism for avionics and control. Really, you could base a whole micro-UAV/UGV system around some version of this concept.
Yeah, that should definitely go in.
I've seen the Arduino drone guys report they've been able to land within 6m of their target. Not perfect, but considering the whole shebang is built by hobbyists for a couple hundred dollars, I'll excuse them.
FIBUA has the unfortunate tendency to produce a good number of casualties because of the requirement to get close. Anything that increases standoff range therefore, can reduce casualties.
Using something like this, you could "clear" a house one room at a time without actually setting foot in it. Use three or four in quick succession for each room. Even though you'd still need occupation via human to ultimately be victorious, the need to avoid the initial assault into prepared defenses will be a godsend.
One "Little Boy"'s tonnage worth of gun-toting quadricopters dropped on a busy city would probably result in more deaths than Little Boy itself did.
(the world is pushing heavily in these directions; scary stuff)