Bounty

In Fallout 3 you can collect bounties from good or evil characters if you pick either the Lawbringer or Contract Killer perks.

Lawbringer
With this perk, the player can remove the finger of every (human) evil character he or she kills. The finger can then be sold to Sonora Cruz at Regulator HQ for 5 caps and a Karma increase.

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 the ear of every (human) good character he or she kills. The ear can then be sold to Daniel Littlehorn at the Scrapyard for 15 caps and a Karma decrease.