SIREN.io - Siren is an investigative intelligence platform.
DataWalk - DataWalk is a software platform to connect numerous large data sets, both external and internal, into a single repository for fast visual analysis.
Netglub - Netglub, the really open source information gathering solution.
sn0int - sn0int is a semi-automatic OSINT framework and package manager
SpiderFoot - Open source intelligence (OSINT) automation tool.
Maltego - Maltego is an open source intelligence and forensics application.