This is a bit of fundamental shift in web design, so I don't really expect to see it. However...
I'd love to be able to manage multiple accounts under one login.
Why multiple accounts? I have one account that uses my "screen name". My screen name is a little silly to use for business, so I have another for work. I'm considering adding another with a less silly name for personal use.
Another thing that might work would be SG address aliases.
Cheers,
Al