What I'd personally like to see is a way for multiple logins to work. Switching between my apps account and my gmail account is horrific. Myself and many others have taken to opening an incognito mode/privacy browsing session whenever we need to access them. Integration, a way to sync mailboxes (that doesn't use pop), or at least better cookie management so I can log out of one then log into the other is what I really want.
Then you can just switch account from the dropdown on the bar at the top, most apps remember which account you use with it, and you can even use gmail with different accounts in different tabs.
I find that solution to be quite decent. Generally, when I hit a google website it will prompt me to pick between my two different accounts. Even using googles oauth will prompt me to pick between the two accounts! Apparently, it isn't supported for some things, but I haven't come across anything yet.
