Earlier quoted context omitted.
I agree. I love OAuth idea and the single-sign on flow. I love having one source where I can go and see all of the sites that have my info, and I love being able to rescind my account from that central location. However, I hate that Facebook/Twitter take it a step further with all of their social integration features to the point where many apps assume, by default, that you want to share share share everything you do…
I'd rather use one with an exceptionally good security policy (including account recovery), realtime multi-modal notification, customizable settings (i.e. being able to ip/geo restrict, rate limit, etc.), etc. And maybe do groups, too. Google Apps for Your Domain could be kind of like this, but isn't. Probably the closest, though. Maybe someone like Dropbox/Box.Net/AeroFS?
Can I email you to talk about your needs a bit? It sounds like you have some good ideas.