http://ysshlyesehcnscptskrpai4iupxccuvfcpbxk37kclbs3rsaqmolzaid.onion/darknets.html
I feel some kind of responsibility to not help out here. There are some client software written for I2P, like forums, bittorrent, IRC, et.c. Most software leaks personal info so that a programmer had to specifically adapt a program for I2P, or write it from scratch, means some effort has been made to anonymize it.