A responsive nav:

• Built using the jQuery-One-Page-Nav plugin
• That switches to a menu icon on smaller screens

Additional responsiveness (besides your nav) that:

• Uses either media queries and/or the Bootstrap grid framework
• Uses at least one breakpoint
• For example, you could do something like the image gallery below.

Makes use of at least one other JavaScript plugin. Some examples (feel free to choose one not on this list):

• Stellar.js (parallax effect) http://markdalgleish.com/projects/stellar.js/
• Fancybox (lightbox) http://fancyapps.com/fancybox/ (Links to an external site.)
• bxSlider (responsive image/content slider) http://bxslider.com/