My husband used to belong to a service organization that used this method of cooking corn at it's barbecues. It was always a hit with that group so we adopted the method for our family/friends gatherings. You can't beat this method for cooking corn for a large group.
You will need the following:
1 medium sized aluminum garbage can with lid (there are several mid-range sizes)
corn still in husks
A medium sized can should hold a case or more of corn. Add salt to your water after you have put it in the can to heat. Once the water is salted and heated it is time for you to add your corn and then put the lid back on. It will take a 30 to 45 minutes for the corn to cook, depending on the size of the can and the size and amount of the corn. My husband says that you can smell that the corn is done. You will want to make sure that your water does not entirely steam away, so until you are used to this cooking method you should check your water. Lifting the lid too often is like opening an oven door too often while baking. Just check it near the end if it looks like the steam is slacking off too much. Add a bit of water if needed.
When the corn is done and removed from the can (tongs needed) pull back the husks to the end of the cob but not off. Remove the silk. You can use the husks as a handle to hold the corn and dip it into your melted butter. A good idea for a container for the melted butter is a clean coffee can. Dip the corn into the melted butter and let the excess drip off. Then add salt if you wish, and it is ready to eat. It is very yummy.
We usually serve the corn as a first course while everything else is finishing up... calms the wild beasties, and if needed you can turn the kids loose outside for a bit with their corn. If you have any questions, please leave them in the comments section, and I will answer them there if I can.