Met the world's thinnest mouse:

[engr mona]

Met the world's thinnest mouse: the DaoKorea's Slim G4. It is only 5mm high and about the same size of a PCMCIA card when folded, actually as it has a retractable cable, you can keep it in your notebook's slot for that card after using.

Specifications:

Dimensions:
when flat: 9.4 x 5.3 x 0.5 cm / 3.7 x 2 x 0.1 inch (length x width x height)
when Active: 10 x 5 x 3 cm / 4 x 2 x 1 inch (length x width x height)
Weight: 43 Gram +/- 10%
Interface standard : USB
Cable Length : 65 cm / 25.5 inch, Manually retractable into the body
Buttons: 2 buttons (Left & Right)
Wheel: Touch scroll wheel
Resolution: 800 DPI
Reatails from £24.99 up to $99 depending on where you buy.