I don't think there is really room for such a fund, simply because the competition is so fierce that you would have to do 100's or more investments to get one that gives you a good ROI. The successful ones can bootstrap, the others die and try again.

One of the more interesting observations that I read on the adult market somewhere (I can't find where, sorry) is that the adult and the gaming industry are the only two 'mature' internet industries, in the sense that the cards have been dealt and new entrants have a very hard time getting traction.

That alone would be a reason to make an investor very skittish.