Making interactive, animated experiences is one of the greatest things about the web. With the new HTML5 canvas based libraries, the power and flexibility of the tools that was once restricted to flash is now available in native HTML/javascript code. One of the articles that hit our desktops today was a comparison of the major web drawing frameworks; Raphael, Processing.js and Paper.js. Raphael is based on older SVG technology and we haven't worked with it much, so we don't really have an opinion on that one. Processing.js we have used before for experimentation as well as an adapted boids animation on our main site. Processing is great for the heavy, complex animation stuff; one experiment was to draw hundreds of moving particles on screen with no noticeable slowdown. The other framework is Paper.js. From what I read and saw on the demos, it looks like a really good way to create simpler but more interactive experiences because of its object oriented focus. Which should you choose? My bet for simple stuff would be Paper.js. However, anything requiring complexity, or fast animation should really be Processing, and because of our experience with and the power of Processing.js, we'd actually recommend looking at it earlier in your development cycle than later. Check out Smashing Magazine for the full throwdown.