http://hctxrvb4yv2ojmpcf46bqzgwvnyj6jkq4ngk3xwyffmj4c67zj57fzyd.onion/about.html
You can read more about safety considerations when collecting data in
the Tor network in " A Case
Study on Measuring Statistical Data in the Tor Anonymity Network " by
Karsten Loesing, Steven J. Murdoch, and Roger Dingledine. In the
Proceedings of the Workshop on Ethics in Computer Security Research
(WECSR 2010), Tenerife, Canary Islands, Spain, January 2010.