One effective idea that I have not seen enough publishers execute is the concept of Value Exchange. For the sites that have valuable, paid content, this is an opportunity for the marketer to play the good guy.

How does it work? In exchange for viewing an ad, the consumer gets access for a full day to the site’s premium content-- content they would normally have to pay for. The marketer sponsors the content for the day, but -- as opposed to offline sponsorships where the consumers can skip past the ad -- the user must view the ad prior to getting access to this premium content.

Here is how Salon.com has executed on this creative idea:

They prominently promote that a user can access the whole site for free that day, compliments of the advertiser-- in this case "The National Geographic Channel."

Once a user clicks to access the site for free, they unavoidably view the ad, which in this case is for a program about the pirate Blackbeard:

Immediately after viewing the ad, the user gets redirected back to Salon.com, where there also happens to be several ads that a user could click in order to see more about the product:

Note: Salon is clearly not the only site that does this.

It is an effective and eye-catching concept. It is not intrusive, and it is likely to generate great awareness about the product being advertised. You would never get this type of exposure through an ordinary online marketplace buy.