The last decade of the 20th century will be remembered for the global Internet. The first decade of the 21st century will be remembered for blogs.

Depending on whom you talk to, blogs are either a loose cannon or the replacement for the mainstream media. The truth, as is often the case, is somewhere in between.

In an interview on Fox News, former CBS executive Jonathan Klein complained, "Bloggers have no checks and balances. . . . You couldn't have a starker contrast between the multiple layers of check and balances [of the mainstream media] and a guy sitting in his livingroom in his pajamas writing." What really irks Klein is the ability of a handful of blogs to put some badly needed checks and balances on CBS.

Charles Johnson, who operates the Little Green Footballs blog, helped prove beyond a reasonable doubt that the documents raising questions about President Bush's National Guard service, presented by Dan Rather on CBS' "60 Minutes" shortly before the 2004 election, were fakes. Using Microsoft Word for Mac OS X, Johnson created a look-alike of one of the alleged documents (sans artifacts of repeat photocopying used to make the document appear old). An animation comparing one of the alleged "documents" with Johnson's re-creation can be viewed here .

I'm not claiming blogs represent a higher standard of journalistic integrity. Klein is right about one thing: Blogs are the unvarnished products of people who may or may not know what they are talking about. But that misses the point. Blogs are useful because they are immediate, interactive and accessible to anyone who stumbles on a truth the mainstream media, for whatever reason, chooses to ignore.

David vs. Goliath stories aside, blogs are here to stay because they deliver unique value. Blogs' publication and distribution costs are essentially zero. It's still generally true that you get what you pay for. But many blogs serve esoteric subjects and interests with small or scattered followings - opportunities the mainstream media consider unviable.

Interestingly, some of the most popular blogs are organized around news reports from the mainstream media. Some post excerpts from stories on obscure topics obtained by scouring the world's media. Others grab stories buried in the back of major newspapers - if not left out altogether - and place them on the blog equivalent of Page One.