Kupfer
Kupfer, "a convenient command and access tool", is a Gnome program that can launch applications and open documents, and access different types of objects and act on them.
Kupfer's main Web Page, with the latest releases is http://kaizer.se/wiki/kupfer/
Feel free to edit and improve upon these pages. It's a Wiki.
Documentation and Workspace
Guidelines for contributing patches to Kupfer: Guidelines and Policy
Started guide for Plugin API: http://kaizer.se/wiki/kupfer/Manual/
Kupfer Project Links
Main Web Page http://kaizer.se/wiki/kupfer/
Mailing list http://mail.gnome.org/mailman/listinfo/kupfer-list
Bug reports http://bugs.launchpad.net/kupfer
Source repository http://git.gnome.org/cgit/kupfer/
Kupfer releases RSS Feed: http://kaizer.se/wiki/kupfer/releases/index.rss