I'm going to be honest here. My main motive for carving jack o'lanterns is to get at the seeds inside and roast them. The art project is secondary to the food.
The actual pumpkin itself isn't very good to eat, as the large jack o'lantern varieties tend to be spongy and tasteless. For cooking pumpkin (which I love to do, roasting thin slices in the oven and using them to top spinach or kale, resulting in sort of a warm winter salad), I think the smaller varieties are much nicer, although Moses the Poodle thinks the large ones are delicious and if I don't watch him closely he can be found with his entire head in the pumpkin, helping himself to a stringy snack.
Once you've plundered all the seeds, separating them from the strings, rinse them well in a colander and let them drain for a few minutes. Then pour them onto a baking sheet, the largest you have--give them all room to spread out. Pour on a tablespoon of olive oil and add 3 big pinches of sea salt and stir them around a bit with your hands. Roast in a 400 degree preheated oven for 10 minutes or until lightly browned. You will smell them when they are done and hear them start to making popping noises, but don't stray too far from your oven (while you are, say, chasing a poodle out of a pumpkin) because they will burn quickly.
The seeds are best just out of the oven, crackling hot, but they also make an addictive snack for your lunch box if there are leftovers. If you would like to get fancy, you can add a teaspoon of curry powder or smoked paprika. When my in-the-process-of-moving sister was out of vegetable oils of all sorts, I've also been known to roast them in a tablespoon of butter, and I have to say that it didn't hurt them a bit.