Create a tag command. (Bookmarking)

Can someone create a tag command to bookmark the page that we are in?
And if the page is already bookmarked the command could show the tags already used.

Adding these features would increase the usability of firefox users that use the keyboard as their primary input device.

Showing the tags already in use would also increase convenience, productivity and all around usability by assuring consistency across bookmark organization.

Thank you very much.