Great service to collect and tag all important stuff :)
Waiting for the desktop (Windows and Mac) app now
Index basically bookmarks stuff, using tags. Evernote does that but also clips whole pages or simplified versions, stores docs, allows rich text, works offline, and lots more. EN has its drawbacks but is overall far more productive. Using Index as a layer on top, as its makers more sensibly suggest when they're not tweeting "Sorry Evernote", would add complexity and require online access all the time.
Tagging is super streamlined, making it the quickest and easiest way to save content and organise things.