Qminder - Qminder works the way it sounds: It helps a company mind its queues.
Leadfeeder - Leadfeeder converts your website visitors into sales. Connect your website's Google Analytics to Leadfeeder and unlock the power of seeing who`s visiting your site!
Zeplo.io - Message queue as service.
Visitor Queue - Better identify the companies that visited your website!
slashQ - Queue management system
Elucify - A completely free software tool that uses crowdsourced data to find business email addresses