This Page is Designed to Last — a manifesto from Jeff Huang for preserving content on the web, where he advocates to keep content on the web available and pledges to keep his site available for the next 10 years.
Having my content in this weblog online since 2002, I can very much relate to this initiative and additionally would like to point to the efforts of archive.org (aka. The Internet Archive).
The wayback machine of archive.org allows to see old versions of websites, even when the website itself is no longer available.
For me personally this became critically useful when the database of my weblog vanished with no current backup and I then used the archived versions from archive.org to restore the missing content.
Thus I would like to encourage everyone to support the efforts of archive.org with a donation.