YAPS 2.5
(Edit)YAPS, Yet Another Password Safe for Palm OS devices. Try this one, it's free, cool and... SAFE!
Yaps uses 256-bit encryption based on the Blowfish algorithm. The two fields "Password" and "Info" are encrypted when they are stored in the database. The key itself is not stored anywhere in the Palm device, so there's no way to find it using reverse engineering. The key itself is generated based on the password you specify to enter Yaps. Passwords are generally the weak point of any such system, since people tend to use short passwords, especially on a PDA. The key is expanded to 256-bit even for short passwords, so the encrypted data is safe.