Seth Godin talks about how difficult it is to sell advertising -- especially advertising in media that are not trackable and cannot demonstrate an ROI.

My first career was in radio and TV -- two of the most un-trackable media there are. I did what I could to fix this problem with our reach-and-frequency software, but their problem is too big for most advertisers to deal with.

Fortunately, advertisers are moving to online advertising, which is a direct marketer's dream. For example, it has become possible to connect Google AdWords placements to shopping cart sales results -- with the ROI for each ad tabulated in Google Analytics (or another Web analytics system).

When advertisers know what's working -- and what's not working -- they are more likely to buy more of what works. This means publications can spend less time trying to sell overpriced (or under-tracked) ads -- and more time creating compelling content.

It's a win for advertisers, readers, and publications.