I made ketchup with the tomatoes I froze this year and I loved doing it that way. You don't have to cook it down nearly as much, just thaw them in a colander in the sink and most of the liquid drains off right then. Saves so much time and hassle.
Another thing I've done is blanch/skin my tomatoes outside on the grill so as not to heat up the house. I do big batches because we eat a lot of tomato based foods. I fill a big tub with water and ice, put two big pots on the grill and turn the burners on high to get them boiling and then pull all the tomatoes up in buckets. Blanch, blanch, blanch as fast as I can work with the two pots going at once and just scoop them out and drop them in the ice water. Once the tub gets full I move on to another and another. And then I pull up a chair and skin when I'm done blanching all I've got. Toss the skins in a bucket that goes directly to the compost. It's the most efficient way I've found to go big batches at once and it saves a lot of heat and mess in the house, too. If I'm freezing them I put them right in gallon size ziplocs as I skin them, if I'm planning to can then I transfer them to large bowls, covering each one as I fill it up and then bring them in and pack jars right from the bowls.