GNOME Software lets users share reviews, but these reviews can't be deleted or edited by users, nor can accounts be banned or controlled, because it's all just tied to a user's local login name. Providing a GNOME web account would allow users to be banned, to manage their reviews, etc. It would also keep users from being able to influence ratings by rating multiple times and leaving multiple comments. GNOME Recipes is looking for user submissions to be included. Being able to share recipes via a web service provided by GNOME would allow those recipes to be updated and other recipes to be found, formatted specifically for the recipes app, from a GNOME database of user-shared recipes. GNOME Web is working on a syncing feature for at least bookmarks (I'm not sure if they plan on history, open tabs, etc). A GNOME hosted service for handling GNOME Web bookmarks seems logical. There are various other apps that would be able to implement backup/restore from a web service. GNOME games could restore scores so that they're preserved across installs. GNOME Books could backup bookmarks when they're implemented, remembered locations in books could be restored across installs. GNOME System Settings could even remember settings -- background, notifications settings, user avatar, color profile, etc.