With iOS 5, Apple finally brought good tabbed browsing to the iPad. No longer do you have to go to the open windows screen and waste all those seconds of your life switching web pages. There is also a nifty little feature that lets you open last closed tabs right there on the tabs bar.
Let's say you're browsing around in Safari. You are opening and closing tabs. But you accidentally close a tab that you wanted to check out later on. You opened it a long time ago, so you don't want to look for it in the history.
To see the last closed web pages and to open them again, simply long press the new tab button marked with a '+'. You will see a pop-up with a list of last closed web pages.
Just tap any page from the list to open it up again.