I've been using JavaScript before quite a lot when creating websites and flash games and whatnot, but usually these were just simple, short scripts, and most of the time they even were so small that they were embedded directly into the HTML.
But recently, I had to dig a little bit deeper and came across the real beauty of JavaScript and realized some of its big features: Only doubles as primitive types, no ints, no floats, no bytes or similar. No classes, no real types, no OOP, but of course, you can build your own ugly class/inheritage system using prototypes and functions. If it is true, and the future really is web apps, then I pity the future software developers who have to write software based on this language.
But at least, there is light at the end of the tunnel, the next version of JavaScript,
ECMAScript 4 / Harmony or better known as JavaScript 2.0, featuring classes and static typing. I hope this language will be finished and implemented soon, because this would mean the real fun with client side web apps can finally begin.