Interestingly, some copyright trolls are known to target porn pirates because, experts say, they are more apt to settle and be done with the illegal-download accusation rather than have their name dragged through the gutter during a court proceeding.

In other instances, companies will purchase the rights to illegally swapped content after the fact, and then go lawsuit-happy chasing after file swappers to make money from penalties and from out-of-court settlements.

Of course, some Hollywood production companies hire copyright trolls to go after people who are illegally swapping their content.

The most recent case involves Voltage Pictures, which is working with U.S. Copyright Group and going after whose IPs allegedly downloaded a copy of the film The Hurt Locker. U.S. Copyright Group sent out letters that demanded between $1000 and $3000 in settlement money from alleged violators--and threatened to sue users for up to $150,000 if they didn't settle.

Just a few weeks before the Hurt Locker case, U.S. Copyright Group for downloading Nu Image's The Expendables.