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.
The Landing Page Cookbook - A guide for makers who want to create better landing pages.
Poptin - Create engaging and high converting website pop ups and contact forms in minutes. With Poptin, you get access to a feature-packed conversion rate optimization toolkit that converts more website visitors into email subscribers, leads, and customers.
Landing Pages in MailChimp - Easy to build, custom landing pages for free
OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and customers.
Landingfolio - The best landing page designs for your inspiration.