There are a lot ideas out on this forum when it comes to “most wanted Apps”. Just have a look at this topic with 519 replies 
. a lot of them are complicated and involve weeks of work for the MaidSafe devs. Just to keep it simple and focus on Web Aps here’s a little idea I would like to propose.
Chatworld
Chatworld is an easy to use App that runs in The SAFE Browser and allows you to have public chats. It uses your public_id as the “username”. When you open the App you’ll see a chatbox called “SAFE Community” which you can join with 1 click. There’s also a button called “Create Chatbox” which allows you to pick a name and open your own chatbox. You can share this name with others and whoever knows the name of this chatbox can join it using a search field in which they enter the name.