"Recoil" - inspired by the marine sniper being interviewed in Iraq around 2005. Kill an enemy at full health in one shot with a sniper rifle.
"interior decorator" - (includes a graphic game change) use an explosive that gets enemy blood on all 4 walls in one attack. Can probably achieve blood spatter using the acid splash programming language already in the game.
"kleptomanic" - take 100% of lootable items from... "a compound"
"chain reaction" kill enemies by setting off multiple mines simultaneously (a personal favorite)
"out of sight, out of mind" use stealth to pass through an area without being detected or killing any enemies
"waste not" complete a combat encounter without missing any attacks.
"cheka" be the sole survivor in an encounter between two factions in a fight you instigate (rat king, gangs in junktown, etc...)
That's all I've got off the top of my head. Maybe some more later.