http://ysshlyesehcnscptskrpai4iupxccuvfcpbxk37kclbs3rsaqmolzaid.onion/darknets.html
Because everyone that uses I2P also participates as relays in I2P, if one hosts a service (an FTP or HTTP service, et.c.) then it is possible to deduce who is hosting the service, by examining uptime of all nodes in I2P and comparing them to the uptime of the service.