Taken from devel mailing list:
"It would be really great if you were able to add plugins to the default list by specifying your own locations for them.
Eg. At my last company I built a plugin that just ran a few common db queries and presented them in a UI. However I had to install it manually, and whenever I made any updates (added new queries, or fixed ui bugs) I had to run around and install or download the jar manually on all the machines. It'd be great if you could add a separate mirror, or URL to the normal plugin list. I think this would be a great and unique feature of jEdit. To be able to easily download any "sanctioned" plugins, or add locations of others.
It could be a great way to kind of allow people to use jEdit as a basis for their own application - kind of how NetBeans and Eclipse provide ways to use their platforms to build your own applications."
Basically, it'd be great if you could add your own URL(location) to the Plugin Manager that would then add plugins to the manage/update/install lists. I would think that the given URL's would just point to an XML file that is the same format as the one downloaded from one of the mirrors. So that they could specify more than 1 plugin if need be.