How do I cook scallops?
Most people I know who cook scallops actually overcook them. I always buy sushi-grade diver's scallops from my fishmonger. These can be eaten raw, and are most delicious when done so. However if you want to add a little extra flavor, and liven up the appearance of these then sear these briefly on a high heat. If you can get these from a quality source (probably not a supermarket) and you're not hung up on eating raw/rare seafood you'll never look back.

Unless your scallops have been soaked in a brine, and you're buying the quality scallops I recommend you don't need to rinse them. Otherwise, rinse them thoroughly and pat dry with a paper towel.

To sear these properly I simply melt a Tbsp or two of butter in a non-stick pan. I use as high a heat as possible (med-high to high) you want to put the scallops in just as the butter begins to barely smoke. I've often seen people suggest using clarified butter, but I'm too lazy to try. Place your scallops in the pan and cook them for 30-60 seconds per side. Don't move them around in the pan, otherwise they won't sear as nicely. This is for scallops that are the size of a small childs fist. If you have smaller ones you might need to cook them less.

Just a brief update because I feel I didn't stress this enough. Fresh, quality scallops are absolutely not intended to be cooked well done. They will be chewy, period. If you are used to them this way, well you're really missing out.