I have been browsing the Web on a daily basis for almost 10 years now, and was browsing irregularly for the 5 years before that. Although I have a pretty extensive collection on links and try to keep it sorted, refreshed and updated, I still run into a problem on certain occasions; when a site is no longer hosted, and simply disappears! We lose real gems this way!
In comes the Wayback Machine to the rescue. Browse through over 150 billion web pages archived from 1996 to a very recently. And it's easy to use too. To start using the Wayback Machine, just type in the URL of a site or page where you would like to begin, and press Enter. Then select from the archived dates available. The resulting pages point to other archived pages at as close a date as possible. Unfortunately, keyword searching is not currently supported, but it may be in the future.
If you've "lost" a site you really liked, do yourself a favour and head over to the Wayback Machine. You might be surprised at what you find!!!