Here are some authoritative Internet sites that will spark your imagination and increase your knowledge about design concepts: .
Six simple machines These six simple machines form the basis for complex machines. To quote from the website: "All six of the simple machines have been used for thousands of years, and the physics behind several of them were quantified by Archimedes. These machines can be used together to create even greater mechanical advantage, as in the case of a bicycle."
Intute - this is/was the metasite for engineering and other science disciplines. Unfortunately, it is no longer being maintained as of Jule 2011. may still be useful.
YouTube videos on how stuff works
ThomasNet is a free comprehensive business directory for finding companies and products manufactured in North America. Has information on 173,000+ companies, 152,000 brand names, and provides links to 8000+ online company catalogs. Also includes CAD/CAM drawings.
Engineers Edge Design, engineering & manufacturing resource.
eFunda stands for engineering Fundamentals. Its mission is to create an online destination for the engineering community, where working professionals can quickly find concise and reliable information to meet the majority of their daily reference needs. Read their about for more details