As a direct reposnse medium, perhaps. A recent study shows that:
Heavy clickers represent just 6% of the online population yet account for 50% of all display ad clicks. Heavy clickers are not representative of the general public.
This is backed up by…
Ninety-nine percent of Web users do not click on ads on a monthly basis. Of the 1% that do, most only click once a month. Less than two tenths of one percent click more often. That tiny percentage makes up the vast majority of banner ad clicks.
So who are people clicking? Well, the most recent study says:
Heavy clickers skew towards Internet users between the ages of 25-44 and households with an income under $40,000. Heavy clickers behave very differently online than the typical Internet user, and while they spend four times more time online than non-clickers, their spending does not proportionately reflect this very heavy Internet usage. Heavy clickers are also relatively more likely to visit auctions, gambling, and career services sites – a markedly different surfing pattern than non-clickers.
Who are these “heavy clickers”? They are predominantly female, indexing at a rate almost double the male population. They are older. What kinds of content do they like to view when they are on the Web? Not surprisingly, they look at sweepstakes far more than any other kind of content. Yes, these are the same people that tend to open direct mail and love to talk to telemarketers.
It seems pretty conclusive to me (although bare in mind that this is US data). Combine this with banner blindness, and things don't look pretty for online dispay advertising, which is probably why it's getting cheaper and cheaper.