The ability to delegate votes to someone you trust, or to vote directly when motivated is one aspect of a Liquid Democracy system. Others include the ability to create Fluid Groups, the ability to participate in Rich Interactive Debate, and the ability to delegate votes to constituted entities defined using Liquid Law.
YOUTUBE fg0_Vhldz-8 A simple introduction to the core ideas of Liquid Democracy.
History of Liquid Democracy
The internal policies of the Paris Commune are seen as the real-world precursor to the more formalized notions of modern delegative democracy.
The Industrial Workers of the World labour union uses multiple levels of democracy, including Delegative Democracy.
Parties Using Liquid Democracy
Pirate Party in Germany, Italy, Austria, Norway, France and the Netherlands use Delegative Democracy with the open source software LiquidFeedback, while in Belgium members of the Pirate Party have developed their own solution called Get Opinionated .