I have been registered for Amazon's Appstore for about a week or two now. Admittedly, only a small sample but I do not find Amazon's free app of the day to really be all that. I will continue to look and see what they have in case something interesting comes along.

Free Apps offered since I joined:
Aces Traffic Puzzle Pack [game]
Astral plague [game]
Casino Blackjack Pro [game]
Daily Ab Workout [personal development:fitness]
Dominoes [game]
Fantastic 4 in a Row HD [game]
Gravity Burst [game]
Mahjong Artifacts [game]
Multi Reps [personal development: fitness]
My First Tangrams [game]
NoteCalendar [productivity]
Radiant HD [game]
Robo 3: Gears of Love [game]
Shopper's Paradise HD [game]
Vegas Bowling [game]
Whiteboard Pro [productivity]
Wikinvest Ad-Free [wealth management]