While I think signs are good and fine, I think being able to write a message on a piece of paper or a scroll would be nice. I think it would be a nice roleplaying element in that you would find old notes and ledgers in abandoned bases and such. Also, I feel like its unnecessarily hard to communicate with your neighbors in salem. By having paper you could curtail ( maybe only slightly) outside-of-client communication, which I think breaks game continuity/atmosphere a little.
Either it could be something you could only buy in Boston from the homeland or you could add a small production line that might just be mulling wood chips, pressing, and drying into paper. Then you could use a quill (made from a feather?) and input text like you do for signs. You could even go a little further and have simple drawing functionality too. Users could create maps and outlines for towns. All in all I think paper would be a big addition for the social life of Salem.
Anyways, What do you guys think?