You can find information & resources of science, biotechnology, chemistry, ecology, technology, science resources, mechanical engineering, earth sciences, astrophysics, nuclear & molecular at PortalScience.com
Engineering ToolBox
Tools and reference data for engineers.
http://www.engineeringtoolbox.com
Engineers Edge
Design and engineering resources and database. Design calculators, forums, specifications, tolerance charts and data.
http://www.engineersedge.com/
Engineers Tool Box
Collection of online computational and reference modules for professional and student engineers everywhere.
http://www.engineerstoolbox.com/
