OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and customers.
Effin Amazing UTM Builder - Add UTM tags to your links from a Chrome Extension
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.
UTMBuilder.net - Easiest UTM tags builder
POPUPSMART - A no-code tool to increase e-commerce sales, build email lists and engage with your visitors in just 5-minutes.
InterestExplorer - Discover 1000's of hidden Facebook interests to target.