Citizen Mundi is a site that simulates how a type of direct democracy would operate. Anyone can join and participate.
In some ways it operates in a similar way to the Interactive Democracy proposed here, with initiatives that may be voted through to a second round debate and final referendum. But, one of its innovations is that your voting power depends on how much participation you have previously demonstrated. This can be measured by the technology. For example "Submitting an initiative is worth 5% towards your participation ratio."
To my mind, the big disadvantage of such a system is that it is prejudiced against in-frequent participants who may have key and detailed knowledge on a certain subject but generally don't get involved in every issue. Imagine if this was applied in the real world: there may be a busy nurse or doctor, with a family to look after, with little time or inclination for politics, but with excellent insight and a keen interest in voting on a health care bill. Indeed some may consider that these people should have more voting power on this issue than a frequent participant with no specialist insight. The proposed Interactive Democracy system doesn't give them any more clout, except that they are free to influence as many people as possible by the power of their well informed arguments.
But to be fair, Citizen Mundi could evolve away from the "participation ratio" system if someone were to propose a change and the vote was carried.
(The name Citizen Mundi means citizen of the world.)