Wayback Machine - Browse through over 150 billion web pages archived from 1996 to a few months ago.
Timehop - Your digital life history
Waybackpack - Download the entire Wayback Machine archive for a given URL
2016bestnine - Your best nine Instagram pics from 2016
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
Likecreeper - Randomly hit like on a friend's horrifyingly old Instagram