What about P2PRep protocol? Is that what you were seeking? Is there a working implementation of it in something?

http://p2pfoundation.net/Reputation#P2PRep
http://www2002.org/presentations/samarati.pdf

Hello,

Does anyone have any thoughts yet on Voucher-safe as a competitor to Bitcoin?
http://beforeitsnews.com/story/315/292/Siddley_Inc._Unveils_A_New_Anonymous_Digital_Currency:_Voucher-Safe.com.html
http://www.voucher-safe.com/