The Internet Archive
Nonprofit organisation established to preserve Web sites by taking regular "snapshots". The Wayback Machine provides links to older versions of a webpage.
https://archive.org/
Matt's Script Archive
Useful, free Perl scripts for many basic tasks
http://www.scriptarchive.com/
Bartleby.com
Online study resources for students.
https://bartleby.com/
The FreeBSD Project
Official home: the definitive resource for FreeBSD information. Descriptions, downloads, documents, community, developer resources, support.
https://freebsd.org/
ibiblio
Large, free, online information database. Visitors can browse through their eclectic collections catalog and contributors can host and share their unique collections.
https://ibiblio.org/
OASIS Open
A site where individuals, organizations, and governments can come together to solve some of the world's biggest technical challenges through the development of open code and open standards.
https://oasis-open.org
The Mail Archive
Huge searchable archive of email list content.
https://www.mail-archive.com/