Here’s a quick sketch of “COAuth” — combined authorization (I know, lame name.) The idea is to support service dependencies and have a simplified the user flow. Chaining is not ideal and leads to user drop-off.
Notice that there is optional services as well as required. The “allow” button is greyed out until all the required fields are approved.
This would definitely be a neat extension to OAuth. 1,000,000x better would be authorizing required services from different service providers. Think using Flickr for photos directly within a Twitter app.
Comments are welcome and encouraged :)