Give me a minute.
Ummm.
I'm usually never the sniper...
Oh, yes, Killing Floor, Half-Life series and Team Fortress 2.
Killing Floor: Crossbow (only scoped weapon) is silent, powerful, and rips through all enemies on its way to the wall and is very useful taking down Scrakes, Sirens and Fleshpounds.
Half-Life: Crossbow (again) makes a nice clunking sound, can pin enemies to walls, is hella fun, takes skill for the bolt to drop and is very satisfying to nail someone to a billboard with a red-hot rod.
Team Fortress 2: Sniper sucks at close range, can kill any class at far range, granted the Sniper is good enough. Not overpowered in the slightest, but can be unhelpful.