Contrary to popular belief, the US did not just start having smart bombs in Operation Desert Storm. Military planners realized long before then that the more accurate your bombing is, the less effort you need to destroy your intended target. US efforts in bomb guidance control during WWII were accelerated by the realization that the Germans were working on the same thing with some success (the "Fritz X" and Hs293 attacks on ships).
One of the results of this bomb guidance development was the AZON (short for azimuth only) bomb. It was fielded with limited success in Europe, and with much better results in the CBI theater. Basically, the AZON was a standard 1000 lb bomb, modified with steering fins and a very bright flare. After bomb release, the bombardier could look for the bright flare and steer the bomb left or right with radio signals.
AZON bomb plans
AZON bomb
Bombing accuracy of the AZON was limited by the fact that the bombardier could only move the steering left and right. To fix this problem, a new system, the RAZON, which allowed steering in the vertical plane as well, was developed. But that is another story.
Further references:
World War II glide bombs
CBI AZON crewmember experiences
AZON project in European theater
The dawn of the smart bomb
Wikipedia article on AZON