Long-range lasers could be used to deter pirates from pillaging passing ships.
The non-lethal laser won't incinerate them to a dusty heap, however; it simply blinds the pirates temporarily and lets them know that they have been spotted.
With a width of a metre, the beam can easily scan the six-metre skiffs favoured by high-sea hijackers and leave them feeling as though they've accidentally looked straight at the sun.
Obligatory eye-patch reference
Lasting eye damage (and thus the need for an eye patch) is avoided as the system self-regulates the intensity of the beam based on range, weather and other atmospheric factors.
Pirate attacks, particularly off the coast of Somalia, have increased in recent years; 2010 saw 430 attacks alone.
BAE Systems studied pirate behaviour (rum drinking, parrot ownership, shanty singing) in order to develop the non-lethal laser and found that an automatic weapon to distract suspected pirates was the best course of action.
Although the laser can't actually stop pirates from invading vessels, it can at least let them know they've been pegged and that the ship is ready for them thus, hopefully, deterring them.
Via New Scientist