Like Gravatar but for everything, not just avatars. Gravatar is a service, where you save your avatar. Websites such as StackOverflow can connect to Gravatar and retrieve your avatar from there. So when you decide to change your avatar, you do it in one place.
On a more abstract level, the problem here is that people and organizations often create some data and basically Ctrl+C Ctrl+V it to different services. Couple of examples:
- RSS subscriptions. If I want to try a new reader, I have to export subscriptions from my current reader and import it to the new one.
- Calendar events. Same problem. Yes, some services can sync with each other but it's a messy situation. Calendar apps must separately implement sync with several calendar services.
- Whenever I want to buy something from a new eshop, I need to enter my email and address.
- Restaurants publish their location, opening hours or photos on Yelp, Google Maps and others. When opening hours change, they need to separately update every service.
- Public transport operators send their timetables to Google and other services.
The solution I suggest is to store this data at the source. People and organizations would have something that's sort of similar to Dropbox, let's call it databox. You have a databox url, such as databox.org/1. Your avatar is available at databox.org/1/avatar. Your RSS subscriptions are at databox.org/1/rss/subscriptions. Opening hours of some company are inside a JSON that's on databox.org/2/restaurants.
The databox URL also serves as a login. So the workflow when trying a new RSS reader is like this. 1) You click on "register". 2) Enter your databox URL. 3) The reader requests a read and write permission to your RSS data. 4) You allow it and the reader fetches your subscriptions.
There are some standardized "subdirectories" (e.g. /rss, /calendar, /tasks) but anyone can create a new standard. For example, a bunch of Linux distributions can decide they will save desktop background and other desktop settings to /linux-desktop.