Mail & Stories
ChestMail
I was thinking something along this would be great. I am not sure how complex it is to install with your current chest permissions. I just think it would be more of an organized way to get letters. I like the current system but I could see this be like a guest book or suggestion box or similar.
http://dev.bukkit.org/server-mods/chestmail/
Redstone Sign
Also, I had a suggestion for your story plugin. I was thinking if you had a sign detection script, anytime someone reads the story with the same code shown on the sign you could allow the option to emit redstone at all locations of the signs if that makes sense. Like this could make people read an important message before a door opens for example.
Regarding Chestmail: This is as I understand it NOT an item to write mail but rather to send items and blocks.
We have the deposit system for exactly that. I am not sure how this is better. We will still need the current system to deal with the lottery rewards. Adding something else that does the same only makes things more complicated.
Redstone Sign: We have been working on this but need to implement it properly, document it etc. It is a bit of a lag issue though. I do not see the signs used enough currently though.