Here are a list of favorite plugins of mine.  This is in addition to Daniel Tal’s list of plugins.  (Please check that you are downloading a current/updated versions to work with SketchUp 8 if you are upgrading.  Things are currently in flux.)

Fredo6’s <a href=”>Joint Push Pull</a>

TIG’s <a ref=””> Extrude Edges by Rails</a>

thomthom’s<a href=””>Selection Toys</a>

Be watching for a new version of Subdivide and Smooth by Whaat