The Clicky Keyboard Directory
Once upon a time, the average computer keyboard was very loud. This was because early keyboards used "buckling spring" technology; when a key was pressed, it compressed a spring until the spring buckled. This action was very loud (it made a definitive "click", and is the reason such keyboards are often called "clicky"), but also made for a keyboard with great tactile response.
These keyboards began to die out after the introduction of Dell's QuietKey keyboards. The Dell keyboards were part of a new generation of keyboards using dome switches, which were much cheaper to manufacture (and also quieter). But in contrast to the decisive feel (and sound) of "clicky" keyboards, these are mushy and soft.
In recent years there has been renewed interest in "clicky" keyboards among people that type a lot. This has led to the creation of a small niche industry making, selling, and discussing these keyboards. Chris Anderson would no doubt be pleased.
What follows is a directory of some of the sites that can help you in your clicky quest.
Matias Tactile Pro 2.0 (with Mac styling)
The ClickyKeyboards.com people also maintain a buyer's guide to clicky keyboards.
Wikipedia has an article on IBM's Model M, the most well-known clicky keyboard.
This was typed on an IBM/Lexmark Model M2.