This will be tough. One problem is that (most, though not all) publishers have taught us to expect a lot for "free". Another is that the world is awash in content, so if you're a publisher, hiding yours behind a pay wall just makes room for someone else to try to have his (ad-supported) day in the sun. Snobs contend, "Water everywhere, but only a few drops (ours) worth drinking." Maybe, but with production and communication costs low, and lots of people out there, there are enough exceptions to disprove the rule. Regardless, focusing on these issues misses the point about where the value for the average reader is today. The future of paid content lies not in the content itself, but in serving two adjacent needs: filtering what's relevant, and helping audiences to use it productively.
Let's look at filtering first, and let's take Twitter as an example. At north of 20 million users, and even with a churn rate fluctuating around 50%, you can't ignore it (and recent research suggests business people are paying attention). The challenge is finding useful tweeters. (Digerati friends please help -- is that what one who tweets is called? Or, is it "tweeps", or "tweeple", or some such?) There are some early stage services probing at this: besides Twitter Search (formerly Summize / monetized via... TBD) and its upcoming "Discovery Engine", there's Hashtags (search by / subscribe to... wait for it... hashtags; monetized via tip jar), Microplaza (tweets from people you follow; monetized via subsidy from parent co, which is an enterprise-focused collaboration platform ASP), Tweetmeme (Digg for Twitter; monetized via sponsorships), Wefollow (like the Yellow Pages of Twitter), plus a half a dozen more I've heard of and tried and doubtless dozens I haven't (see here for more). (Michael Yoon and I are working on one, stay tuned.) Is some refined, scalable version of one or more of these systems worth $2-3 bucks a month to some reasonable sub-segment of the Web-using public? Related memo to Google: it would be worth $2-3 month to me to have Google suggest good posts from my blogroll (I use Google Reader) based on parsing my emails, which it currently does to serve me ads in Gmail.
Second, and perhaps potentially far more lucrative, are services to help audiences do stuff with content. Be an affiliate for schools that sell courses related to the content, for example. Last time I checked, the market for education, particularly online / just-in-time education, was growing at a healthy clip. More simply, offer lectures by content authors / editors and sell tickets to these events, or be an affiliate for others who do that with your content.
My favorite creative approach to segmenting audience needs and monetizing accordingly comes from the musician Jill Sobule, whose http://jillsnextrecord.com/ (scroll down to "A Message From Jill") does a nice job of unpacking all the reasons why folks engage with her music, and then pricing related offers accordingly. Folks wonder about Myspace's future, what with the Google deal expiring soon and all. I wonder: does Jill's approach suggest one path might be to leapfrog Eventful and function as an uber-agent for the bands making their homes on Myspace?