Calling the popular note taker known as Evernote a "site" is giving it short shrift. Yes, you can access this repository for notes, images, audio files and other snippets of information from your browser. But there are also Evernote apps for iPhone, iPad, Android, Windows Phone and webOS. And a bevy of third-party applications and services allow you to save stuff directly to your account. The items you put in Evernote are never more than a few taps or clicks away, letting you use it as an infinitely expandable, absolutely reliable extension of your memory.