Blacktree
Quicksilver
FreeAccess applications and personal data by typing abbreviations.
Mac
Nocturne
FreeChange your display colors in ways more suited to low light conditions (such as at night).
Mac
iTunes-LAME Encoder
Freeconvert cd & aac to mp3 with lame
Mac
Secrets
FreeTweak hidden prefs in Apple and third-party apps.
Mac
Chime
FreeListen to an hourly chime marking the passage of time.
iOS