[sdiy] center tapped pots?

[Steffen]

On 08/04/2007, at 3.32, peter edwards wrote:

>  center tapped pots

Sorry about my noobness and potential disturbens of this thread.

But what is the trick with center tapped pots - how do they work?  
I've have searched my electronic book, and tried to search the web  
where i found an article <http://www.answers.com/topic/center-tap>  
which doesn't, unfortunately, cut it straight to me.

Thanks.