Bounty

In Fallout 3 you can collect an ear or finger from Good or Evil enemies after you defeat them, if you pick either the Lawbringer or Contract Killer perk. A Bounty will be paid for every ear or finger turned in to the appropriate NPC.

Lawbringer
With this perk, the player can remove a finger from every Evil human or non-feral ghoul character he or she kills. The finger can then be sold to Sonora Cruz at Regulator HQ for 5 caps and a Karma increase. Characters with a particularly high karma rating will receive 10 caps per finger, which Sonora describes as a 'bonus'.

Some specific characters have larger bounties:
 * Junder Plunkett's finger can be traded for 1000 caps.

Contract Killer
With this perk, the player can remove an ear from every Good human or non-feral ghoul character he or she kills. The ear can then be sold to Daniel Littlehorn at the Scrapyard for 15 caps and a Karma decrease.