I'm currently running a mybb board that isn't supported with the notifications, but when reading the documentation about the notifications i saw that it is connected to the user. This connection is the reason i can't really be bothered that i don't have such a thing running but one thing i would like to see is notifications in the chat room about new topics being made and new replies being posted.
One thing that Arrowchat has done is that it has lowered the amount of posts and topics. I would like to boost this again because not everybody checks the chat often is is likely to miss something (because it only shows 100 rows back). This could easily be done by posting notifications about whats happening on the board (not with the users in particular).
I know an announcement bot (or whatever) is currently not supported, but it would be greatly appreciated. Not only by myself i'm guessing.