The official IE blog points out a useful new feature included in Internet Explorer 8: You can login to the same site with multiple accounts—simultaneously.
Using the feature is easy enough—use the Alt key to temporarily show the menu bar, choose File -> New Session, and a new window will open allowing you to login to another account at the same site—extremely useful for logging in to multiple web-based email accounts at a time.
If you have the need to login to multiple accounts on a regular basis, you can take it a step further and add the -nomerge parameter to a new Internet Explorer shortcut, which will simulate the New Session option and open a new window.
