Scratches, like wrinkles are inevitable. If it bothers you, buy one of they myriad cases available.
More good Apps:
"Crosswords" - By 'Standalone Inc.' Great crossword game.
"Units" - FANTASTIC, must have utility. Convert any measure. Time, volume, currency, area, length, speed, energy...wow...
"Wordpress" - For bloggers
"Evernote" - Save (and have transcribed) audio, text, or photos. Take a picture of a whiteboard and it'll be transcribed for you.