One of the coolest mods I've played is Josh's Farmer Mod. It lets you buy fields and plantations and let's you upgrade them from the money you make off your harvest. He was able to correct all the bugs and unbalancing aspects of the mod, and was saying he wanted someone to take over the work.
I don't know if there are any active modders that would be interested in tackling this challenge, but it's a very worthy one. There are almost no farming mods out. In fact, the closest I found was Ules Farm and that seemed cool, but entirely different.
I'd help in any way I can. Please let me know if anyone wants to take on this project.