User-generated content can be a great supplement to your own content. The most famous example is Amazon's book reviews, which date from 1996 (not exactly "2.0."). Communities, which were the main recommendation in the 1997 book Net.Gain, are also an old idea.
Community features are particularly useful on intranets, and many of the Intranet Design Annual winners offer them. The reasons communities work better on intranets also explains why they're often less useful on the open Internet:
A company's employees are an actual community with a crucial shared interest: succeeding in business.
Employees are pre-vetted: they've been hired and thus presumably have a minimum quality level. In contrast, on the Web, most people are bozos and not worth listening to.
Although some intranet communities — such as those around internal classified ads — are aimed at lightening up the workplace, most intranet communities are tightly focused on company projects. Discussions stay on topic rather than wandering all over the map.
Intranet users are accountable for their postings and care about their reputation among colleagues and bosses. As a result, postings aim to be productive instead of destructive or flaming.
Small groups of people who know each other are less susceptible to social loafing, so more users contribute to intranet community features. In contrast, Internet communities suffer from participation inequality, where most users never contribute and the most active 1% of people dominate the discussions.
Realistically, most business tasks are too boring to support community features. The fact that the city Sanitation Department will pick up Christmas trees sometime after December 25 isn't likely to inspire a longing to discuss shared experiences on the department's site. Users will visit the site to find the pick-up dates and rules. Nonetheless, the Christmas tree pick-up page is an example of how government websites can offer taxpayers great ROI: if done right, this one page will save the city from answering endless phone calls — each costing $10 or more. Often, such boring, workhorse stuff is where the money is.
