I discovered GWT (Google Web Toolkit) a little while ago and I'm really impressed. It's basically a toolkit that lets you design web applications in java and then translates them in javascript. Brilliant!

Using GWT and GWT incubator to support the HTML5 canvas API, I have developed a simple but addictive solitaire after suggestion from a friend of mine (thanks Carla!). It's deployed on appspot at this address. And here's a screenshot (click on it to go to the game):