List of Essential/Helpful SketchUp Plug-ins

Here is a list of the plugin's. They are all free. Although some require you to register (for free) to Sketchucation.com to download them.   This is what I consider my core plugins.  Without these SketchUp is pretty useless for designing mechanical/product-like items. 

I use to have a real CAD package that I had put down some cash for.  But my computer that ran it went down, so I made do with SketchUp until I could get a new computer.  After being forced to use it I realize once it's decked out with the neccesary plug-ins it gets pretty darn close to the more professional cad packages. Still has nothing on the likes of Solidworks etc... but I don't have a few grand to throw at it, especially after throwing a giant chunk of change at a fully decked out refurbished 27" iMac. 

As far as other free cad packages go... I think they are all pretty abysmal and I have tried about every one available.  At least SketchUp has lots of cash behind developing it, and good prospects for continued future development. Plus there are some big benefits in the novice user department, big user base, a more gentle environment for the uninitiated.  Point is if you put some time into learning it, you can accomplish just about any modeling project without spending too much more time then you would in a more professional streamlined package. 

Plug-ins, a necessary evil to free under-powered software.

If there are more you have suggestions for let me know. I just thought it would be good to start a list of essential/very helpful solid plugins.