Here's the first drone bomber.
It's the RQ-7 Shadow armed with a Shadow Hawk smart bomb (Mike Hanlon over at Gizmag did a great job with his article).
Drone + smart bomb is a scary combo. Why? As Hanlon points out, it is much cheaper than the manned alternatives. The solution for maintaining expansive ambitions despite shrinking budgets.
Over the longer term, tech trends dictate, we're going to see this type of system get less and less expensive. Also, each generation getting smarter and smarter, eventually reaching a high level of autonomy.
Given the precision of this smart bomb (8" from over a mile away), you don't need much explosive to do signficant damage.
In an anti-personnel role, we'll see smart glide bombs shrink to 1/2 a pound apiece or less. The smaller the better.