Use Internet Explorer 8 to Access Multiple Gmail Accounts
Here's a little-known advantage to using Internet Explorer 8: It lets you access multiple Gmail accounts simultaneously and independently.
This is accomplished via the New Session option, which makes it possible to log onto Web sites that track your identity across different tabs--like Gmail.
In Firefox, for instance, you can't have multiple Gmail accounts open in multiple tabs or Windows. If you sign into a second one, you'll get signed out of the first one when you try to do anything. Here's how to take advantage of this IE8 perk.