Bandana (gives you infinite ammo) - Beat the game. Select Tanker. Get over 30 dog tags.
Blue Wig (gives you infinite 02) - Find all the dog tags.
Brown Wig (unlimited ammo for Raiden) - Beat normal mode with more than 100 dog tags
Orange Wig (infinite grip) - Beat the game with 150 dog tags.
Shaver - Grip yourself over behind the caged fence when you start with Raiden.
Stealth Camo - Beat the game. Select "Tanker". Get more than 60 dog tags.
Stealth Camo #2 - Beat the game with 120 dog tags.