Some vegetables require a quick blanching before you freeze them in order to preserve their color and flavor, while others can go straight into the freezer. Here's a quick guide on what falls into which category.
Peppers (sweet and hot)
Parsley, cilantro, dill, chives
Rhubarb (pack in sugar)
Peas (shell, snow, or snap)
Leafy greens (alternatively, saute)
Winter squash, pumpkin
Eggplant (unless it's in a dish like ratatouille)