Freezing tomatoes isn't only super easy, it's the best way to preserve their fresh tomato flavor to use once tomato season is over.
To freeze tomatoes: Put tomatoes in resealable plastic bags, suck excess air out (you can use a straw to do this), seal, and freeze. It's just that simple and easy. During tomato season I keep a bag in the freezer and just pop in tomatoes we can't eat quickly enough.
If, however, you have a lot of tomatoes to freeze, try setting them on a baking tray and putting them in the freezer for a few hours to freeze through before putting them into bags (this method helps ensure the tomatoes freeze quickly and evenly).
Note that there is no need to peel tomatoes before freezing them - the skins will slip right off after being frozen.
Use frozen tomatoes in any recipe that cooks fresh tomatoes (pretty much any tomato sauce or even this Tomato Puree fits the bill). While they will retain a great fresh tomato flavor, the texture will be too compromised to be used raw. Unless, that is, you thoroughly puree and strain them as in this Fresh Tomato Sauce.