Omega Centauri Software
Listen to audio through your phone's earpiece when you earphones aren't handy.
Completely change screen colors (red on black night vision mode, set gamma, etc)
Send reduced resolution photos by email/text/etc with minimum number of taps.
Download free audio books from the LibriVox collection (need an audio player)
Change screen colors (red, sepia, BW, set gamma, etc.) for fun and night vision.