If you have a lot of tabs open at a time, it's sometimes quicker to have Ctrl+Tab switch to the most recent tab instead of the next one to the right. This is the default setting in the Tab Mix Plus extension for Firefox, so a lot of you are probably used to it.
To make Internet Explorer use this behavior, go to Tools \ Internet Options. Click on the Advanced tab.
Check the box for "Use most recent order when switching tabs with Ctrl+Tab". You'll need to restart IE7 for this change to take effect.