A simple app I'm sure users would appreciate would be a timeline. Being reminded about caches, warbands, and other D&Ds, and being notified of the current Prif rotation is useful. Something else that can be added in at the bottom is a list of the current portable locations, as provided by the Portables fc.
The Prif rotation and warbands is listed on the Jagex Clock.
I have a simple version that I use and host locally, but I thought the general users would find something similar in the main app to be useful. http://prnt.sc/c368oc
Well my coding is garbage as I never intended to share it but alright.
timeline.html - The page that the user accesses, reuses a bunch of JS from AFKWarden with some modifications.
timeline.php - The JS endpoint used to avoid any cross site request nonsense.
memory.php - A simple memcache class I made a long time ago. Used in timeline.php to avoid spamming any twitter, or otherwise, queries.
TwitterAPIExchange - The Twitter php class I used.
Everything else I believe was either offered in your libraries or pulled out of AFKWarden.
That should be everything you need to decide if you want to rehost it. Oh, you'll also need a Twitter app to access their API.