My best ever Engineering Links to Great Sites by Geesaman:

These are the best set of engineering sites I have found

  On line Machine Engineering Information

These are additional listings:

AFE Association for Facilities Engineers
ASME American Society of Mechanical Engineers
Cabling Design for wiring and cable design engineers
CadPortal.Com for engineering professionals.  
Design Engineering
Elec-Training.Com Online electrical training
Electrical & Computer Engineering Resource
Electrical and Electronics Engineering, Britannica
Electrical Circuits & Systems, Pearson
Electrical Devices & Electronic Components Circuits
Electrical Schematic Diagram
Electrical Wiring for the Home, Dan's Wiring Page
Engineering Central for Engineering Professionals
Engineer Supply.Com 
Eng-Resource.Com Technical-Industrial Directory
Eng-Tips Technical Work Forums for Engineering. 
Job Search Engine for Mechanical Engineers
Mechanical Design Engineering Resources
Mechanical Design Resource Page
Mechanical Diagram, TLV
Mechanical Drawing, Britannica 
MIT Mechanical Engineering Department
Mechanical Engineering Magazine Online
Mechanical Engineering Portal
Mechanical Products, Laird Plastics
Mechanical Products, Services & Resources
Mechanical Service Contractors of America
Offshore Well Installation Diagram