archive.today is your personal Wayback Machine!
It takes a "snapshot" of a webpage that will always be online even if the original page disappears.
This can be useful if you want to take a "snapshot" a page which could change soon: price list, job offer, real estate listing, drunk blog post, ...
It saves a text and a graphical copy of the page for better accuracy.
It also shortens URLs much like tinyurl, goo.gl and bit.ly do.
It can save pages from Web 2.0 sites even with hashbang URLs, for example http://archive.today/https://twitter.com/#!/medvedevrussia and http://archive.today/http://wikimapia.org/#y=25226684&x=55158491&z=14&l=0&m=a
It can save dynamically generated SVG: http://archive.today/2013.05.01/http://nickqizhu.github.io/dc.js/
Saved pages will have no active elements and no scripts, so they keep you safe as they cannot have any popups or malware!