Simple Signup Form – jQuery Plugin
Pantherius
Build responsive sign up form with email notification. Provides Visual Builder and lot of customization options.
Pupunzi (Matteo Bicocchi)
This plugin let you play any public YouTube video as background of your page. It can also be used as a customized player in page.
Customformsjs – webforms made by engineers
Mitermayer Reis
Javascript Library to aid on creation of beautiful form elements