I feel so geeky for knowing this. It's awesome.

It was used in, IIRC, the Bacta War, when Rogue Squadron resigned from the Alliance in order to make war on Ysanne Isard and the Lusankya, which had blockaded essentially all of the Bacta in the galaxy. Rogue Squadron purchased ~300 proton torpedo launchers and targeting computers.
The targeting computers all went to the space station that Rogue Squadron was using as a base at the time. As Rogue Squadron attacked the planet, Booster Terrik, who was in charge of the station, warded off a full-scale attack and forced the surrender of an Imperial Star Destroyer - which was overwhelmed by the 300 torpedoes its sensors reported were trained on it.
Meanwhile, Rogue Squadron began engaging the Super Star Destroyer
Lusankya in battle. As the battle raged on, Corran Horn drew a bead on the Super Star Destroyer and locked on with his X-wing's targeting computer. Nobody thought anything of it until all of the X-wings and a large number of freighters all launched upon the Super Star Destroyer, overwhelming its shields and ending the conflict.
It may have been used other places as well, but that's the most significant use that I can think of.
