Twitter Bootstrap is a front-end toolkit for rapidly developing web applications and websites. It is a collection of CSS and HTML conventions. Twitter Bootstrap is built on LESS. LESS extends CSS with dynamic behavior such as variables, mixins, operations and functions. At the moment i build most website and webapplications with Twitter Bootstrap. Examples Streetart.nl, PKDigitaal, Gizzing and JongerenChat (under construction) and many others.
Most of these websites are build with OpensourceCMS.eu which has been rebuild with Twitter Bootstrap.
Jamedo websites also offers responsive webdesign based on Twitter Bootstrap. Jamedo websites uses the excellent framework of Skematik for WordPress in most cases. Skematik is a GPL WordPress theme + framework designed with Twitter Bootstrap to be the best thing for WordPress ever. With Skematik Jamedo Website build sites like Bougemagic.
I create Twitter Bootstrap templates you can download for free from github. You can use them to see the technics used to build them. To use them in a production environment you will need a designer definitely.
The first example template is a One Page Sale design. The page has a responsive slider (example page without slider is include too). You can add your product or service, special offers, usp and testimonials. An order page is include too.
The second template set shows you a web shop with vertical menu. Included are homepage, product page, categories and search page.