The short answer is almost anything.  To name but a few:

• Laptop
• Mobile phone
• MP3 player
• BlackBerry
• PDA
• Skis
• Tennis Racquet
• Golf Clubs
• Sunglasses
• Pager
• PSP
• Camera
• Handycam
• Projectors
• USB
• Keys

      Whatever you have that is too valuable to lose.