A company which markets assorted PDA
cases and accessories. Rhino Skin is known for its titanium
cases for Palm
organizers. These have had various product names, but most people know them as "Rhinoskins". They are really pretty indestructable, though they add significantly to the Palm's bulk (or lack thereof)-- the package still fits in a (pant) pocket.
This is a pretty good tradeoff-- you weren't honestly planning to carry your PDA in your shirt pocket, were you?