http://www.instructables.com/

Instructables is a website specializing in user-created and uploaded do-it-yourself projects, which other users can comment on and rate for quality. Once registered, members can create Instructables that are step-by-step descriptions of projects they want to share online. They are written in such a way that they easily allow other members to replicate, and share with the rest of the community. Members can also upload videos and slideshows, depicting a project that they have not documented.