This
is probably the smallest USB keyboard availble as of now.Its 170 X 73 X
15 mm approximately and almost gets placed in your palm.  Availble at a
price of 25$ flat is very cheap if somebody is looking for an ultra
portable keyboard. You can see the details at@ Super-Tiny Keyboard.

Smallest USB Keyboard

Features:

• Low keycap notebook keyboard with 56 KEYS
• Fn/Num lock change function
• Static resistant magnetic, field disturb resistant
• Silent switch feeling, feel comfortable
• Small, lightweight and portable
• Slim body that save working place
• Available USB port
• Dimension: 170 x 73 x 15mm (approx.)
• Weight: 116g