I've had this idea for awhile now, but no way to execute it. I wanted to share it anyway.
I've always liked the appeal of mods which expand on vanilla Minecraft. One of the ideas I had was expanding on villagers and villager professions, focusing first on farming.
I would love to see a mod which lets you hire villagers to farm for you. You'd first have to find a village (obviously) to recruit some villagers to work on your farm. Once you've established some farming ground, you designate a hired villager to a certain area, which it will farm for you. You'd link it to a chest in order for it to gather and deposit items, and to a bed to sleep.
They won't do it for free though. In the early stages of your farm you can pay your Fillagers by providing room and board, let's say 10% of what the farm produces. But, you can also pay them (with emeralds maybe), which will increase their efficiency and lets you keep all that is harvested. Increasing their pay will increase their efficiency (capped), and maybe add some other bonusses.
There are other ways to increase efficiency, by providing them with proper tools for the job. Hoes for a regular farmer, fishing rods for fishermen, axes for tree farmers and something I haven't thought of yet for cattle farmers. Just like in vanilla, upgraded and/or enchanted tools yield increased efficiency and/or effects. However, since upgraded and highly enchanted tools are pretty easy to acquire even in vanilla, I imagine there being some cost to equipping your fillagers with new tools. Maybe an increase in salary is required, or a learning period. This will make it so tools of lower rank won't be useless during a playthrough, and players won't just skip them altogether in favor of upgraded and enchanted tools.
What I like about this concept, besides the fact that it expands on vanilla, is that there's actually a reason to build out your farms, where most other mods don't really require you to build very much. So I imagine this concept would appeal most to people who actually like to build in Minecraft, in favor of one block solutions.
There are so many ways you could go with this I wish I had the ability to develop it myself, but alas, I neither have the knowhow nor the energy for it...maybe someday.