Devour a corpse (Cannibal perk required):-1 Karma per corpse
Stealing from a non-evil character or faction:-5 Karma per instance (note that when stealing from owned (red text) containers, such as cabinets or lockers, the Karma change applies once per activation of that container. Meaning, if you open a container once and steal two items, you lose 5 Karma, but if you open the same container twice, stealing one item each time, you will lose 5 Karma each time, which means you lose 10 Karma). Items can be replaced in owned containers after being stolen, and then stolen again and again with the same Karma loss each time, making for a useful method by which console gamers can decrease their Karma, although repeatedly hacking an owned terminal is a faster way of doing this.
Repeatedly hacking an owned (red text) terminal (Classified as stealing, but can be done over and over again)-5 Karma per hack attempt, NOTE, even accessing the terminal will result in negative Karma
Some companions have a Karma level requirement that must be met if the player wishes to enlist them:
Clover and Jericho need a bad Karma to be recruited. After being hired, they will follow the player regardless of changes in Karma level, although they will often mention how boring the player is, should he become good.
Butch DeLoria and Sergeant RL-3, both recruited with neutral Karma, are similar to Clover and Jericho. They will not leave if your Karma becomes good or evil, but unlike Clover, you can't get them back with a high or low Karma level when the main story separates you.
Players with high Karma may hire Fawkes or Star Paladin Cross. They are not slaves or servants like Clover and Charon - they will follow you of their own free will, without any cost, if you ask them and have good Karma. Be aware, however, that being good characters, they will leave your side if you become evil after hiring them, and will refuse to follow you again until your Karma is high enough.
Dogmeat and Charon will follow you regardless of what your Karma level is.
Some of Three Dog's news will be based on the player's Karma. Which can be odd if you are evil and have done something good or if you are good and have done something bad. Such as he will call you a jackass for sending Bryan Wilks to Paradise Falls, and then compliment you for saving Megaton.
When the player's Karma is in either the good or evil end of the spectrum, Talon Company (with good Karma) or Regulator (with evil Karma) hit squads can appear and ambush the player. These hit squads appear as random encounters and as ambushes at specific locations where the player exits structures that utilize loading screens to return them to the Capital Wasteland.
When the player has neutral Karma, Talon Company/Regulator hit squads do not spawn. However, Talon Company and/or regulators that spawned previously will not disappear or become friendly to the player. They will always be hostile upon contact regardless of the player's current Karma.
A player that has been both good and evil may sometimes find themselves attacked by Talon Company mercs and Regulators at the same time where their ambushes occur. The two morally opposite groups will often attack each other if they notice the other group before noticing the player.