Wayback Machine - Browse through over 150 billion web pages archived from 1996 to a few months ago.
blit - Automated, scheduled, screenshots to your inbox.
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
FreezePage - FreezePage is a free service for taking online snapshots of web pages.
Archive-It - Archive-It is a free to use web archiving service designed for the libraries and archives.
Bypass Paywalls - Bypass Paywalls is a web browser extension to help bypass paywalls for selected sites.