You'll find bins full of corn at farmers markets and supermarkets. These usually aren't your parents' ears, though – remember the old advice about the only way to cook it was to have the water boiling when you went out into the field? New varieties of corn have been bred to be sweeter and to hold on to that sugar longer before it converts to starch. It's convenient corn.
How to choose: Ears should be well filled out (check the tips of the ears to make sure there are kernels), and make sure the silk is still soft, not dried out. Don't shuck the whole ear before buying, though; it makes the farmers really cranky.
How to store: Corn should be refrigerated, tightly wrapped.
How to prepare: If you haven't already tried grilled corn, you really need to. Soak the un-shucked ears in water to cover for at least 30 minutes. Then toss them on the grill. Turn every 5 minutes or so until the corn is golden; it'll take about 20 to 25 minutes total. Shuck them before serving and the silks will come off with the husks.