For the love of everything that's holy, stop adding these totally useless social media bars that are floating on top of your potentially interesting content. This entry is unreadable on the go, I'll probably forget to come back later today and the only thing I'll recall is that there was another "of those" useless submissions.
I open a new window (tab) with the OAuth process and since I opened the tab I can redirect to some quick closing script and my main code is waiting for the auth process to finish. Once it does the user is through. Easy peasy.
In the front end I just poll every few seconds for the oauth completion and the server says "yup I'm done" or "they're still working on it" :)
Would you end up writing your own OAuth provider in that case?
For node/Express, passport.js is a good option (but doesn't help you out with the database at all) -- http://passportjs.org/guide/username-password.html
Django has basic user authentication built-in, Ruby on Rails has Devise - https://github.com/plataformatec/devise and AuthLogic - https://github.com/binarylogic/authlogic.
I'd recommend reading the Ruby on Rails security guide about user management to get an idea of some of the challenges in building an authentication system: http://guides.rubyonrails.org/security.html#user-management
If you want to write an OAuth provider here's a great PHP tutorial: http://djpate.com/2011/01/13/how-to-write-a-complete-oauth-p...
But as I've commented, having built edgeyo and Strangers for Dinner and having tested in-page (iframe) and redirected authentication, redirected authentication seems to garner more trust
