5. A method of determining a reputation score for each node in a directed graph comprising: providing, to a computer, the directed graph comprising a plurality of nodes, and a plurality of links, wherein each of the plurality of nodes represents an autonomous entity and each of the plurality of links represents a positive opinion which a source node of that link holds of a target node of that link, generating, by the computer, a reputation score for each node having at least a value of positive reputation by performing one or more random traversals and counting visits to each node by incrementing a per-node counter wherein a generating comprises: counting at most one visit to each node per traversal, so that a reputation score of a particular node is not increased by having a link to other nodes that links back to the particular node, and returning a final reputation score for the particular node, wherein the final reputation score is a value of the counter of the particular node divided by a sum of counters for all of the plurality of nodes.
5. A method of determining a reputation score for each node in a directed graph comprising: providing, to a computer, the directed graph comprising a plurality of nodes, and a plurality of links, wherein each of the plurality of nodes represents an autonomous entity and each of the plurality of links represents a positive opinion which a source node of that link holds of a target node of that link, generating, by the computer, a reputation score for each node having at least a value of positive reputation by performing one or more random traversals and counting visits to each node by incrementing a per-node counter wherein a generating comprises: counting at most one visit to each node per traversal, so that a reputation score of a particular node is not increased by having a link to other nodes that links back to the particular node, and returning a final reputation score for the particular node, wherein the final reputation score is a value of the counter of the particular node divided by a sum of counters for all of the plurality of nodes. 7. The method of claim 5 , wherein when a node is visited during a particular traversal, the node is removed from consideration as a candidate destination node for a remainder of the traversal.