Samsung has put a bunch of proprietary software on the Galaxy S III (S3) and some apps, like S Memo are particularly useful.
There are lots of note-taking apps for Android. Some of them sync with cloud servers like Google Drive and others sync with desktop note-organizing apps like Evernote.
Samsung has attempted to create a proprietary note-taking app that syncs with all these services, uploads to Dropbox and allows you to post your notes to your various social media networks. In short, S Memo tries to be all things to all users, and, surprisingly, it does a pretty good job.