Where can I find SketchUp Ruby Plugins?
SketchUp maintains a Warehouse just for Extensions. Everyone that has SketchUp has access to the Extension Warehouse from inside of SketchUp. That is our favorite place for finding and distributing extensions.
The Extension Warehouse is not the only place though that offers extensions. You can also find a number of free and commercial scripts at:
From:
http://developer.sketchup.com/en/content/faq
https://sites.google.com/site/sketchupsage/resources/plugins
https://sites.google.com/site/sketchupsage/resources/plugins