Evernote is a free app for your smartphone and computer that stores everything you could possibly imagine losing track of, like a boarding pass, receipt, article you want to read, to do list, or even a simple typed note.
The app works brilliantly, keeping everything in sync between your computer, smartphone, or tablet.
The basic version of Evernote is free, but it limits you to adding 60MB of new notes a month, lets you sync between only two devices, and doesn't include advanced features.