As I’ve been through most of these at one point or another, and finding them is a pain in the ass:
- Apple Mac OS X Human Interface Guidelines
- Microsoft XP ‘Design Guidelines’ (or Buy the book argh)
- Palm OS Application Design Guidelines Pre PalmOS 6; and Post PalmOS 6 (aka Protein)
- Java Look and Feel Guidelines (Version 2)
- Gnome Human Interface Guidelines (Gnome-HIG)
- KDE UI Standards
I’m of course still stuck with a PalmOS 4 handheld, so the pre PalmOS6 docs are what I refer to the most. I have no real motivation to buy another handheld when they’re looking like the entire market is going to be eaten by micro PCs like the OQO.
[links edited, text slightly changed 2005-10-14]