Almost unlimited supply of inventory in the online ad space combined with automated delivery via adsense have combined to drive prices on regular inventory so low as to be a marginal contributor to income across most publisher sites.
Certain demographics can buck this trend and targetted sites can draw sponsorship but straightforward banners are commoditised.
Video pre-roll as devices converge and the possibilities or very direct targetting come into play looks more promising perhaps but again the issues is excess supply.
Since it's Friday a quote from the French writer Celine "If you aren't rich you should always look useful" plus a picture of the hottest girl in Wales (apparently).
Iolo adds: actually, the problem at the moment is that there is not enough quality video delivery to show ads against since the market is so fragmented, this isn't helped by the fact that video targeting is a pipe dream: the ad industry is much more focused on behavioral targeting since they make more money that way.