This website provides a web-based index for plugins for Trimble’s 3D-modeling software SketchUp. It is a community-driven portal where users can find plugins easily and rate and discuss them. There is also a small plugin that lets you browse this site directly from within SketchUp. All of this is available without registration.
In addition, any user can contribute plugins (including various metadata) and blog posts (after a review). Simply register using the small form on the bottom of the page and you are set to go!
More information is on the About page. At this point, this site is in Beta-mode, so go ahead and provide feedback in the blog.
PLEASE NOTE: With the arrival of SketchUp’s own Extension Warehouse and the SketchUcation PluginStore, this site has basically become more of a proof-of-concept than a functional addition to SketchUp. Feel free to use it if you like, but note that plugins on this site might not have been updated in a while.