Not satisfied with the mechanics of other sign edit tools, such as requiring the use of commands, I went and threw together a plugin that lets you edit signs simply by right-clicking them with another sign in hand.
Download here. (Older versions available here.)
If you are upgrading from 1.6 or earlier, be sure to set up your database info in the config before you start up your server with the updated plugin.
When you right-click to edit a sign, you can then view and edit the text of the sign just as you would when creating it. You can only edit signs if you are the owner or if they are owned by everyone. To include colours on the sign, use the & character followed by a digit or a letter from A to F. This works both when placing and when editing. If you want to include an & character on the sign, and the plugin interprets it as a colour code, simply double it and the plugin will realize that you don't want it to be converted.
To see who owns a sign, hold a stick in your hand (you can change this to any item in the config file), and right-click the sign. To change who owns a sign if you have permission, hold a feather in your hand (you can change this to any item in the config file), and right-click the sign. Then either type the new owner name into chat, or walk over and punch them. You can also enter the symbols @, #, and * into chat to set the owner to yourself, no-one, or everyone, respectively. You could also edit ownership by editing the config file, but since signs are stored by their location that would not be an easy task.
To configure the items used for setting/viewing the owner of the sign, simply set the "view-owner" or "set-owner" values in the config file to the ID of the item you want to use. You can also change the "allow-stacking" and "break-protect" values if you wish. It's probably a good idea to leave the "signs" section alone since that keeps track of who owns which sign. You can also configure it so that you need to be sneaking (or not sneaking) to edit signs.
Video by Warby579 aka UltiByte:
List of things to maybe do:
