[antonlitvinenko]

From user perspective having several sign-in options is a source of confusion: first day I sign in with Facebook... next day I come in and don't remember which service I've used to sign in with? And this time I try Twitter only to see none of my data.

How do you guys solve that problem? I think, this might be even the bigger problem than having 20% or 30% "drop out" on sign up process.

[ArchD]

You'll probably see that you don't have an account registered with the website through Twitter, not "none of my data". As a user, if you like FB more, you'll likely try FB login first. If you like Twitter more, you'll likely try Twitter login first (if available).

[nknight]

Isn't the obvious 80% solution a separate cookie that just says "this browser last logged in using service X" that the server can use to give UI cues?

[antonlitvinenko]

With single device - you're right... but this becomes really a problem when you expect your customers to use multiple devices: computers at home, at work, smartphone, iPad...

how would you suggest your customer which login to use the first time she tries to sign in on another device?

[Drbble]

Ask for username/email, then key off that. 80% solved.

[rogerbinns]

Would that be my personal email account, my gmail account, my other gmail account, my university/alumni address, my work email or the other work email?