Time warp
http://www.archive.org/web/web.php
The Web is constantly updated with new content. This makes it the ultimate resource for research and news.
But there's one problem. If you need to find something you read in the past, it could disappear. I can't tell you how many times it's happened to me.
Well, the Internet Archive is taking on the task of archiving the Internet. Enter an address, and you can see archived copies of the page. You may find the story you're looking for. Or, it's just a fun way to see how the Internet has changed.
I like it so much that I installed the nifty toolbar button. I just dragged it to my browser's toolbar. Now, when I'm visiting a page, I just click it to get an archived version.