Hmm... off the top of my head, I can mainly think of my suggestion I posted a few months ago, which was for allowing multiple announcements to be made, without having to overwrite the previous one. The user will see the most newest one and can click the 'history' button to view the past ones like they can with notifications.Yes. Announcements are fully intact, and I was actually thinking about ways to improve them. Any suggestions?
Another idea could be the ability to add variables in the announcement, such as their username (for other variables, the admin could define them via the admin panel according to their users' table) as it could help make them more 'personalized'. You could even use the variables to add display conditions if separate announcements were made possible, but that might be getting too complicated.
And while I don't use them, the ability to target them to different groups could be useful to some. Also, the ability to edit the announcement after posting without 'resetting' it for everyone would be great!
Well, that's pretty much what I could think of for now, but, do as you wish and see fit for AC :)