Meta Box Conditional Logic
Add visibility dependency for custom meta boxes and custom fields in WordPress
Gravity Perks
A WordPress plugin adding a series of helpful features ("perks") to the Gravity Forms plugin.
Ninja Forms
A complete form creation suite for your WordPress site, clients, or application development.
WP Ninjas, LLC
Gravity Forms
A full-featured WordPress plugin for custom forms used on more than 1,000,000 websites.
Rocketgenius