The CraftBook plugin has some great features that I'm sure people would pay a small price for. Couple things that come to mind are pipes, which can be used to transport items through lines of glass blocks. Useful for item sorting and organizing shops. Auto crafters. Example... I can have iron ingots automatically craft themselves into Blocks of Iron. Very useful for saving space. Autobreak signs & crushers. Possibly too OP, unless you can limit the amount of each that people can have. I haven't looked into that. Numerous other features. There really is just a ton of features in it.
I came across this old post of mine. Normally I don't gravedig, but seeing as I'm the original poster I'm going to re-open this. I'd still like to see this plugin, specifically the auto crafting feature, added. I haven't used CraftBook in almost 2 years now, but I assume it has the same, if not more, features now. https://www.spigotmc.org/resources/craftbook.2083/