The iTunes App Store offers downloads of several applications for Apple iPhone, iPod touch, or iPad for free, as listed below. At up to $4 off, each is at the lowest price we've seen. The deals:

• Monster Burner for iPhone, iPod touch, and iPad: Tower defense-type game
• iBoost: Turbo Your Car! for iPhone and iPod touch: Vehicle soundmaking tool
• Celestial Defense for iPhone, iPod touch, and iPad: Adventure game
• Pocket Tie Guide for iPhone, iPod touch, and iPad: Necktie-tying reference
• HungrySquid for iPhone and iPod touch: Puzzle game
• Chess App for iPhone, iPod touch, and iPad: Board game simulator
• Bunny Popper for iPhone, iPod touch, and iPad: Reaction-time game