Scott Kirsner has another great post about the internet evolution and how to make money off media on the web. Of special interest is this income breakdown from the folks who brought us
FOUR-EYED MONSTERS :
Arin and Susan shared a lot of financial info about 'Four Eyed Monsters.' They've grossed about $135,000 from the movie so far (but are still trying to erase some credit card debt.) About 69 percent of that has come from selling DVDs, movie tickets, and downloads, and 31 percent has come from selling t-shirts, posters, and other merch.
This speaks profoundly to the genre audience who are in general terms more predisposed to buy merchandise of things they embrace - action figures, t-shirts, underoos, posters, books, etc... This sort of thing should figure into any production you mount for the web. 31% is nothing to sneeze at.