I'm guessing he's asking for applications that will enable him to push his cards to their limits. The EVGA Precision Tool or Riva Tuner will work fine for overclocking
The triple buffering option will only be used when you run v-sync in your games and it will ease the jumps when your framerate drops below your refresh rate. Double buffering = 60/30/15... etc, tripple = 60/45/30... don't rememebr the numbers here, but the first one after 60FPS is the most important imo (going from 60 to 45 and not 30).
Other programs? Games

That's what those cards are for in the first place. Fire up Crysis or Warhead. Or perhaps try the MechWarrior: Living Legends mod for it? STALKER Clear Sky likes to murder cards when maxed. You got nVidia cards, so perhaps some hardware PhysX-enabled games? Cryostasis or Batman: AA perhaps?
As for encoding, no idea here. You might want to wait for someone who knows more about CUDA-enabled applications.