dradis - Dradis is the open-source reporting and collaboration tool for IT security professionals.
UCINET - UCINET for Windows is a software package for the analysis of social network data.
Lampyre - Lampyre - an efficient data analysis and OSINT multi-tool for everyone.
Gephi - Gephi is an open-source software for visualizing and analyzing large networks graphs.
Netglub - Netglub, the really open source information gathering solution.
Graphviz - Graphviz is open source graph visualization software. It has several main graph layout programs.