Simplest possible examples of HTML, CSS and Javascript:

Collection of hacks and demos showing capability of HTML5 apps

CSS3 list scroll effects

↪️ Ridiculously Responsive Social Sharing Buttons

Riding carousels with jQuery.

A lightbox gallery plugin for Bootstrap

A basic responsive grid for winners. This project is based on Chris Coyier's post on grids http://css-tricks.com/dont-overthink-it-grids/

Smooth scrolling and smart navigation when user scrolls on one-page sites.

An open source Javascript framework for detecting the Adobe Flash Player plugin and embedding Flash (swf) files.

jQuery plugin for creating interactive parallax effect

A jQuery plugin that will create a booklet-like component that let's you navigate through its items by flipping the pages.

A simple jQuery plugin to display current weather data for any location and doesn't get in your way. Now supports HTML5 GeoLocation!

m3u playlists for radio music, sorted by popularity

jQuery easy ticker is a news ticker like plugin, which scrolls the list infinitely. It is highly customizable, flexible with lot of features and works in all browsers.

A responsive jQuery-based vertical news slider

A jQuery plugin for displaying stuff in a highly customizable carousel.

A jQuery plugin for building a presentation-style web pages

Very minimal scroll hide jQuery. Hide on scroll down. Reveal on scroll up.