In Call of Duty 4: Modern Warfare multiplayer, I use the UAV Jammer perk for all my loadouts. If you're not familiar, that means my character is hidden from enemy radar except when I fire my weapon (and not even then if I'm using a silencer). I don't just use UAV Jammer for sniping. I use it in combination with machineguns, shotguns, SMGs... everything.
I play Ground War mode exclusively, which means close to 18 players in every battle. The maps are small enough that you're likely to encounter an enemy or be shot every 10 seconds or less.
The result is an experience that I have had in no other game: high-speed stealth.
Stealth in games usually occurs at a slow, strategic pace. Opportunities might appear for only seconds at a time, but you can remain hidden from danger as long as you want... strike when you please.
In my CoD4 matches, on the other hand, stealth is pressured and tactical (the difference between strategy and tactics is that tactics is done on-the-fly, often in response to unexpected events). There is no place to hide where someone can't pick you off with a sniper bullet, a grenade, or knife in the back. Also, enemies are always changing position... and fast.
Stealth in Modern Warfare can mean nothing more than being aware that an enemy is around the corner while he's not aware you're there, allowing you a split-second advantage when you meet face-to-face and he's the only one who is surprised. Or it can mean coming up behind a whole group of enemies undetected while the rest of your team attacks from the opposite side.
This is an uncommon type of gameplay that entire games could be designed around. Try swapping your Stopping Power or Juggernaut perk in CoD4 with UAV Jammer sometime and see what I mean.