The iTunes App Store offers downloads of several apps for Apple iPhone, iPod touch, and iPad which have dropped in price, as listed below. At up to $4 off, most are at or near the lowest prices we've seen. The deals, all with applicable platforms noted:

• ProCamera for iPhone and iPod touch for 99 cents ($2 off): Photo capture utility
• The World by National Geographic for iPad for 99 cents ($3 off): Cartography reference tool
• Bad Piggies HD for iPad for 99 cents ($2 off): Physics-based game
• Eufloria HD for iPhone, iPod touch, and iPad for $2.99 ($2 off): Ambient strategy game
• Flight+ Track Live Flights for iPad for $1.99 ($1 off): Flight tracking utility
• Zombies, Run! for iPhone and iPod touch for $3.99 (pictured, $4 off): Immersive reality running game
• Riven: The Sequel to Myst for iPhone and iPod touch for $3.99 ($1 off): Puzzle game