This is a working list of all known external Inkscape extensions, with a link to where it can be downloaded. It's part of a project to have all or as many extensions as possible available on the website (https://inkscape.org/en/download/addons/). So it will be changing over time. Note that it does Not include the extensions listed on this page http://wiki.inkscape.org/wiki/index.php/Extension_repository.
If anyone knows of extensions which are not on either list, please let us know. (You can contact me here.)