For a long time, until today, I thought that in order to find a (weblog) community it was required to have both a list of inbound and outbound links. This incorrect line of thinking stems from the difference between finding possible members in a community and the actual members. To be a member of a community it is necessary to have at least one inbound link to the community (by definition) and given this simple axiom it actually suffices to have reference to inbound links only to find the entire community. I'll skip the proof given that it is trivial by thinking about a "community member" with 0 inbound links to the other community members, 1 inbound links and then applying mathematical induction.
Tools such as Technorati and BlogPulse either discovered this independently or their Web 2.0 impetus prompted them to implement the inbound links (Who links to me) in their interfaces, while considering that outbound links (Who I link to) are not very interesting for most users.
Suddenly, finding potential weblog community members appears rather easy :-).