Sumo - Free tools to grow your email list.
GetSiteControl - Website popup builder & email marketing suite for ecommerce
OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and customers.
ExitMist - Exit Mist is a new affordable tool for creating professional exit-intent popups.
OptiMonk - OptiMonk is the most powerful Onsite Retargeting platform, that helps you increase the conversion rate of your site, and get more leads by recovering lost visitors.
OptKit - Real-time conversion optimization platform.