Often times when searching for information on the internet you'll find a link to exactly what you are looking for... and then you click on the link and see this:
Here are a couple of ideas on how to still see the site...
#1 - Google Cache
If you found the link on a Google search, simply hit the little down arrow next to the link, and click "cache":
This will show Google's cache of the page even if the website is currently down. You will see this at the top that shows the date that Google cached the information:
#2 - Internet Archive Wayback Machine
Google Cache works great most of the time, but what if the dead link you are trying to get to isn't in Google's cache, or what if you need an older version of the website than what is in Google's cache? That is where the Internet Archive Wayback Machine comes in very handy.
Simply go to the Wayback Machine website, and put in the URL for the dead link you are trying to get to in to the search box.
You'll see options for which dates the Wayback Machine has copies of the site, and you can select a date to see what the site looked like on that date. You will have a bar at the top of the screen where you can select different dates for the site:
Note that it generally all of the snapshots in the Wayback Machine are over 6 months old, but it has saved me many times by being able to find sites that disappeared from the web years ago.