Archive.md - archive.is allows you to create a copy of a webpage that will always be up even if the original link is down
Perma.cc - Perma.
Wayback Machine - Browse through over 150 billion web pages archived from 1996 to a few months ago.
Estonian Web Archive - Estonian Web Archive is a digital archiving library working under the supervision of the National Library of Estonia.
Archive-It - Archive-It is a free to use web archiving service designed for the libraries and archives.
Cached View - CachedView claimed to be the provider of Google caches pages of any website at the moment listed in the index of the Google search engine.