Bootstrap registration forms are easy to use and responsive. I have collected top 6 bootstrap 2 and bootstrap 3 responsive registration forms here:
Bootstrap 3 all-in-one authentication web forms designed in various styles for your mix & match.
Responsive three themes included with Light, Black, Grey colors form, also works as a modal popup.
Dark And Light Themes Available,Flat Style Forms,350+ icons,Retina Ready
Typical Bootstrap registration form.
Sleek-kit Clean and Simple Form HTML & CSS. Its well commented mark-up, W3C Validate mark up and Easy to use.All major Browser Supported.Its Bootstrap Grid form pack. Sleek kit is simple, clean and fresh modern form pack hat useful to agency, company , portfolio, etc..
Modal Log-in for WordPress provides you with a beautiful alternative log-in for your WordPress powered website based on the popular Twitter Boostrap, a front-end toolkit for developing web applications. It supports bootstrap 3 as well.