Demoex (from democracy experiment) has a representative in Vallentuna, a suburb of Stockholm. Any local resident over the age of 16 can vote on issues that the council are about to decide and their councilor then re-presents their view. Anyone can get involved in the preceding online debate if they can write in Swedish. Demoex held this seat for more than 8 years, winning three elections, but lost the recent election after amalgamating with other direct democracy advocates to create a national party, Direktdemokraterna.
Denny de la Haye founded a UK branch of Demoex and ran in the 2010 UK General Election. Please see his comments below (thanks, Denny - I've updated this post).
Demoex also have a presence in Brazil.
Lista Partecipata is an Italian initiative using a similar concept as Demoex. Their slogan is "The control of government in the hands of the citizens (and not only at election time)".
Senator On-Line is an Australian political party which proposes to have no platform but rather to act based on online polls.