i think you are going to have to offer up more specifics on the type of structure you have in mind. what type of construction, etc.? otherwise, i would say, why do you need a footing at all if the structure is only temporary? for example a tent doesn't need a footing. a trailer doesn't need a footing, etc.

I am looking into putting customized 40' shipping containers on a site. I do not want to place them directly on the ground because of water runoff and topography. I was assuming there would be some sort of steel footing that spreads point loads for this specific case.

You might try helical piers: http://www.helicalpierworld.com/
They probably require some expertise and equipment to install, but have the advantage of resisting uplift. Alternatively, how about adjustable jack stands meant for auto repair or you could use a short scaffolding if the site is sloped.

google pin foundation. diamond pier makes a nifty little pier.

thanks ether, this is exactly what I was looking for.

those pin foundations from diamond pier are amazing - I have never seen anything like it.

how Shigeru ban make stable structure without using a footing?