A useful feature of Gmail Manager, a great Firefox extension that notifies you when you receive new Gmail messages, is that you can easily log in to a different Gmail account without entering the username and password: after adding your Gmail accounts and Google Apps accounts, select the account by right-clicking on the Gmail Manager icon in the status bar and then click on the icon.

Another way to easily switch between your Gmail accounts is the Google Account Multi-Login Greasemonkey script, but it stores the passwords in a non-secure way.
Hopefully, Google will add a feature that lets you link a main Google account with your other accounts and log in once to access all your Google accounts, like you can do in Windows Live Hotmail:

If you want to minimize the number of times you access your secondary Gmail accounts, forward all the messages to your main account and enable it to send messages using custom From: addresses.
Labels: Firefox extensions, Gmail
This is cool but probably they have to make it more secure. And I believe most of the peoples have more than one gmail account.
Mike said on January 14, 2008 5:13 PM PDT:
But will it work with Google Apps? Everybody with Google Apps has a base google account too, which means they almost always have two gmail accounts to log in to.
macbeach said on January 14, 2008 5:33 PM PDT:
Google used to have something in their ToS about not allowing multiple accounts. Did they ever take that out? Unless so I'd be afraid to admit that I had two accounts (if I did, hehe).
said on January 14, 2008 6:00 PM PDT:
macbeach I have the same question...
At least it seems we should not worry anymore, afterall tracking duplicate accounts isnt that easy for google.
orhan said on January 14, 2008 6:00 PM PDT:
you can not use "an" article before words which are pronounced like /you/. "an useful" is wrong.
The upside of google apps accounts is you can log into each domain once.
I have 3 google accounts and can switch between them at will.
I still dont see a point why you will have to switch. Best is to have one more (than the ones you are already using) gmail account and have all your accounts forward mails to it and also add them as a sender. Infact you can even define tags per gmail account. I am doin it from ages ;)
Jeton said on January 15, 2008 2:18 AM PDT:
It's worth mentioning that Gmail Manager has been acting weird lately, like not showing new mails on the inbox. Google Talk reports the new mails but Gmail Manager doesn't.
@Mike:
Gmail Manager works well with Google Apps accounts.
@macbeach:
No, somebody misread the TOS and created this weird legend.
Gmail's program policies say you must not "create multiple user accounts in connection with any violation of the Agreement or create user accounts by automated means or under false or fraudulent pretenses".
@orhan:
Thanks for noticing my mistake (English is not my first language).
@Lakshman Prasad:
You may store different information in other Google accounts.
@jeton:
Make sure you have the latest version.
Dav7 said on January 15, 2008 5:38 AM PDT:
Hopefully, Google will add a feature that lets you link a main Google account with your other accounts and log in once to access all your Google accountsI hope soo!!
Installed this early this morning. Loving it already!
I too would love to have this extended to more than just Gmail. Google Apps, Reader, Analytics, Adsense and Adwords to name a few. Hopefully this will be in a future release? Pretty please?
I use Gmail manager which is fine but sometimes I forget to check my accounts...
I now have set up msg forwarding to my main account and the send from.. BUT I don't like the way it says on the sent msg :-
From:1234@googlemail.com on behalf of Miss xxx (missxxx@googlemail.com)
So it shows your other email account which defeats the purpose of having another account for other types of mail - ie friends, work etc..
said on January 19, 2008 11:13 PM PDT:
"Hopefully, Google will add a feature that lets you link a main Google account with your other accounts and log in once to access all your Google accounts"
What if you click "Edit" from your Google Accounts page.....then see:
"Associate email addresses with your account, Adding email addresses helps Google associate useful information with your Google Account. For example, Google Calendar can show invitations sent to any of your addresses."
dusty said on March 19, 2008 11:52 AM PDT:
The idea is to have accounts for different activities and to avoid any linkages between them. I want to open each account when it is needed.