A few demos on thewebrocks.com

crop/ A demo of how you can use the context menu and canvas to provide in-browser image cropping
cuberollovers/ IE=edge,chrome=1
browserid/ IE=edge,chrome=1
videooverlay/ IE=edge,chrome=1
3D-css-tester/ IE=edge,chrome=1
mdnmgm/ Making a MGM style intro with the MDN logo and CSS transitions
smashing-events/ Events refresher article on Smashingmag demos
doublesun/ Undoing the lame 'double sun' in Star Wars: A new hope. Just drag and drop it.
interaction-cam/
smile/ Because sometimes you want to leave a rotating trail of smileys on a page.
time-yourself/ A quick game to test your sense of time.
audiosprite/ IE=edge,chrome=1
html5catcher/ HTML5 catcher is a simple game to catch falling elements. You can use the keyboard, move the mouse or tilt your phone or tablet to move left and right
intros/
bunnies/ IE=edge,chrome=1
html5-3d-css/ Making the HTML5 logo rotate in 3D space with CSS transformations
browsermemory/ initial-scale=1.0; minimum-scale=1.0; maximum-scale=1.0; user-scalable=0;
brickdeck/ width=device-width, user-scalable=yes
3D-photo-rollover/ IE=edge,chrome=1
targetgallery/ An image gallery in pure CSS using :target
cubes/ A rotating cube using 3D CSS transforms
touchtest/ IE=edge,chrome=1
zoom-and-pick/ Zoom and pick is a client side tool to pick colours from an image and create the CSS from the chosen colours
canvasthumber/ Batch generate thumbnails by dropping them into the page.
mozhtml5/ IE=edge,chrome=1
x-tag/
audiofade/
bounce-a-horse/
pigs/ Flying pigs in Canvas
what2pack/ width=device-width
postercircle/ A demo showing off the power of CSS 3D transformations.
irregular-shape-rollover/ width=device-width
mozilla-monument-name-finder/
beaniemaker/ IE=edge,chrome=1
gradientsio/ Curated gradients for designers and developers.
game/
mozmonument/ width=device-width
context-menu/ How to use detect support, hint availability and make context menus dynamic.