DoubleRecall has an interesting scheme that may make publishers, advertisers, and customers happy.
A publisher who wants to put content behind a paywall can offer DoubleRecall ad units, which requires a reader to read a short message and type in a couple of words (highlighted by the advertiser) to gain access to the content. This unlocks the article for a limited time, or can provide other benefits (like virtual goods) to the reader.
DoubleRecall says their research shows this process boosts name recognition by 11 times over traditional methods. Ads can fetch a CPM (cost per 1,000 impressions) of $120, which is about 10 times as much as a traditional banner ad. There's also a social ad at the end of the content that allows the user to retweet the brand message, reply to the sponsor or click through to their web site. DoubleRecall says they've been getting a 12% clickthrough rate on these ads.
Some of this may be due to the novelty value; I'm not sure how well people would like this if they had to go through the process again and again and again, on multiple sites. Still, this is an interesting idea for web sites and mobile apps as well. Part of the success depends on their ability to find plenty of advertisers; let's hope they have some luck with that.