SIREN.io - Siren is an investigative intelligence platform.
AnyMailFinder.com - Find anyone's email address
DataWalk - DataWalk is a software platform to connect numerous large data sets, both external and internal, into a single repository for fast visual analysis.
Hunter - Find all the email addresses related to a domain
SpiderFoot - Open source intelligence (OSINT) automation tool.
Mailmeteor - Send hundreds of personalized emails with Gmail.