Volunia

The Volunia project closed (see the company side below).

The technology side: For descriptions of the Volunia project (in its first stage of development), among the tons of web resources and news announcements of the time, see for example: Search Engine Land's "Volunia, A Social Search Engine, Says The Web Has Come Alive" Search Engine Watch's "When Will Social Search Engine Volunia Deliver its Quantum Leap"

The company side: At public launch time, the creator has been kicked off his own project by the funding venture capitalist, who wanted to take full control of the company (including the CTO position...!). Result: two years with no innovation, no marketing, nothing, bringing the company to failure. (As an aside, general piece of life advice: despite your enthusiasm and good faith, never trust anybody, as you never really know a person. Beyond words and appearances, you can really find anything, good but also bad: from honest gentlemen to greedy thieves, from judicious men to obtuse egomaniacs. Always shield yourself from the legal viewpoint.) Back to the Volunia project: the (only) positive side is that after the legal struggle, the creator is at last going to get back the whole project code, which will be soon made open-source, so to let other people freely reuse the wealth of code and algorithms developed at the time. Stay tuned for the code, and good luck with your ideas!