Evernote is a note taking application and organizational tool for the Mac and PC. The Evernote iPhone app is a free download that will autmatically sync your notes from your Mac to your iPhone. So you can add some notes on your Mac and then find them later on your iPhone. You can also add notes on your iPhone and have them sync the other way. This includes handy photo and audio notes. The basic service and software is free, with a premium version for heavy users.