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Have you heard of Mininova? It's only the 52nd largest site in the world according to Alexa, and the largest BitTorrent tracker around. Dutch anti-piracy body BREIN estimates their traffic (Google translation from Dutch) at over 30 million unique visitors per month and a total of 5 billion downloads. Their earnings, according to BREIN, count in the hundreds of thousands of euros per month.
And yet, the Dutch-based site has eluded legal action until now. Partly, it is because of their takedown policy; if a copyright owner asks them to remove a torrent from their database, they will comply.