Take a look at Wikis

Wiki Targets How-To Buffs

If you are thinking about starting a new site, one thing to consider is the Wiki model. From the article:

Hannah launched the wiki in February as an extension of eHow.com, another website that he bought last year. EHow had once been a promising internet startup, but the site fell into disrepair following the collapse of the dot-com bubble four years ago. Its database contains close to 100,000 pages of assorted how-to instructions, but without regular updating, entries were looking stale.

By launching a volunteer-supported site for how-to directions, Hannah saw a way out of the staleness problem. Because anyone can edit or add information on a wiki, an active group of volunteers ought to ensure that postings are up-to-date.

It is fairly easy to set a Wiki up using open source software (e.g. TikiWiki, phpWiki). Then it is just a matter of attracting an audience that is willing to get involved.