Ever open up the fridge to find your lettuces or herbs looking a little ... tired? Shock them in an ice bath to perk them up.
Place lettuces or herbs in a large bowl of ice water (or if you're working with a lot of lettuce, fill your clean kitchen sink with ice water), and shake the greens around a bit to perk them up. A minute or two should do the trick. A quick toss in an ice bath will also help to clean the greens, dislodging bits of dirt.