One of the most useful features that Firefox offers over Internet Explorer 7 is the ability to re-open a tab which was closed. Several times myself, I have closed a tab accidentally in IE7 only to have to try to dig it up in my browser history. This is no longer a problem with the IE7 Open Last Closed Tab plugin.

The description on their website explains how it works:

This is very useful when you accidentally close a tab that you didn’t mean to close. Instead of trying to find it in your browser history, you hit “Alt-X” and it automatically reopens in a new tab. It also supports a Quick Tab Style View, shown when you hit “Alt-Q”, which gives you thumbnails of the previous tabs you’ve closed (like the built-in IE Quick Tabs, but for previously closed tabs). You can then click on the thumbnail of the page you want to open in a new tab.

Enough said. This plugin is complete free and definitely something worth having.