Ukelele is a Unicode Keyboard Layout Editor for Mac OS X versions 10.2 and later.
Ukelele aims to simplify keyboard layout editing by providing a graphical interface to .keylayout files, where the desired characters can simply be dragged onto keys as needed.
1Keyboard is a virtual bluetooth keyboard application for OS X.
Turn your Mac into a Bluetooth keyboard that works with all of your devices, comfortably type on your iPhone, iPad, Apple TV or game console.
Vimari is a Safari extension that provides keyboard based navigation. The code is heavily based on ‘vimium’, a chrome extension that provides much more extensive features.
Vimari attempts to provide a lightweight port of vimium to Safari, taking the best components of vimium and adapting them to Safari.
Vimari doesn’t (yet?) offer the vim movement commands you’d expect, but it does link hinting very well.
Shortcat is a keyboard tool for Mac OS X that lets you “click” buttons and control your apps with a few keystrokes. Think of it as Spotlight for the user interface. Shortcat leverages the Accessibility API, which is supported by all applications that come with Mac OS X and most applications.
Control all your streaming radio and online music apps using the media keys at the top of your keyboard. Play, pause, skip and rewind songs just like iTunes, even when Chrome is in the background.
A full 5-row keyboard including arrow and Esc/Ctrl keys, intended for [Android] tablets. Are you missing the key layout you’re used to from your computer? This keyboard has separate number keys, punctuation in the usual places, and arrow keys.
EVE helps you to learn shortcuts, in order to increase your productivity with Mac OS X. Every time you execute an action using the mouse, EVE will show you the matching shortcut.
At the moment, EVE only works with menu items and GUI elements in Safari, Mail, Chrome and the Finder, though support for ‘almost all apps’ is planned.
CheatSheet shows you the available shortcuts of the active application after holding the command-key for 2 seconds. Then a panel will show up displaying the shortcuts of the application you are currently working in.
I can see this being incredibly useful to folk who are new to OS X, and existing users who are learning a new, complex app.