Please keep in mind these ideas are hypothetical, you don't have to argue about if they will work or not.
Another Idea, an automatic 'Online List' that will, well automaticly show who is online so we don't have to keep pressing 'Who is online' when ever someone leaves or joins to update the list.
Stackable cabinets is another one I have been thinking about. Cabinets should become stackable until they are dropped and have items put into them, This could also be done with crates and wind cabinets.
A hunger bar perhaps? To keep track of how hungry you are and when you need/should eat.
While eating, you will get full, but you will still be able to consume food that will do nothing to your health. Perhaps when you are full, a message will show up in chat saying something like "You could not eat another bite!" and it won't consume your food.
For the mappers/admins how about removing layer 1 and making tiles block-able by right clicking them while in 'WE' and having something to show the tile is blocked or not. (This idea was in another game and it worked very well. I take no credit for this idea)
I've always thought that the water tile looked a bit...dull, how about adding a little animation to it to make it look like its wavy or moving slightly.
I've had a hard time finding out where to buy things and knowing how much they are, so how about a marketing system?
More to come! I will be editing this post when I think of other ideas that I would like to share. Remember, you can throw in some of your ideas too!