So here are multiple suggestions in one topic, I hope you don't mind.
First suggestion would be jobs. The server would set up jobs that players could apply for. Example would be; harvest wheat/crops and put into chest (Could be a shop(admin shop maybe) where you could buy the gathered wheat).
If you have any ideas for any jobs please post them below.
Also, if the job-part is a good idea I could come up with more suggestions my self.
Second suggestion is the Auction House (AH).
This would be a room/house where you could put your offer down on paper/books/signs and show them off. Interested players will be able to hang up a note (paper/book/sign) telling the seller and all other interested players their offer. Other interested would then be able to bid higher than the ones before. Auctions would run for max. 3 weeks (can be discussed) and must be sold to the last bidder.
There is much more to be discussed, IF this idea comes alive. I will first get into further detail then.
Notes: Auctioneer(seller) would be able to see who had the last bid before deadline via logblog.
Third suggestion, was already mentioned in the first though and it is sell-to-admin-shop. This would be a great opportunity for every player to earn some $ other than from mining. The price offered would 'of course' be low because you would be able to sell a lot (Prices might be extremely low to prevent exploit).
I made these suggestions because I think the server needs more than one way of earning money (mining) and this would maybe boost the trading between players (hopefully). Some players aren't able to sell items to other players because they've gathered the wanted/needed material them selves and with the jobs they might earn enough to actually buy anything from the admin shop.
Hope you like my ideas
Nioghy