Hi there,
Have you tried SU Sandbox tools? You should enable it first, since they don´t appear in SU by default http://sketchup.google.com/support/bin/answer.py?hl=en&answer=38496
As for the plugins, you could try Sculpt Tools http://forums.sketchucation.com/viewtopic.php?f=323&t=20781&hilit=plugin