Artcontext has been online since the 1990s and advertising has never been used to support it. For several years the site contained links requesting donations to help with the expenses, and to make it possible to produce new work. But that didn't raise much money, so this is where we find ourselves. Stuff!
Online art, or Net Art, is not really sustainable unless there's some revenue stream. Since art institutions, foundations, and the state have done little to support it, this is one more direction to explore. The ephemera on sale here could conceivably defray some of the costs. It's hard to imagine this paying the rent, though.