The Internet Archive
A non-profit collection of millions of freely accesible texts, books, video, music, websites, and more.
An archiving system that allows you to explore the past-web. Built on open-source tools, commissioned by Rhizome.
The Software Library Archive
An arm of archive.org, the software library contains over 60,000 freely accessible software programs, including a formiddable collection of iconic early computer games.
A resource and research hub holding a huge collection of documents and media related to developing theory and philosophy.
Needs no introduction, I am sure.