Excellent plugin! Works really well and the option to add multiple signs is great! Allows me to give my staff perms to sign and players can now collect the staff signatures on their custom items boosting server interaction amongst players and staff but also the server economy as players attached a higher value to signed items!

Add an option to make some specific item cannot have signs.
For example, if an item have a line of lore called "This item cannot be signed", player will be denied to use /sign when holding this item.
And you could also add some charge settings to make sign itself more unique.