The infamous Joel Spolsky writes about ways in which HTML, CSS and JavaScript need to be improved to make it possible to implement smooth user interfaces in browsers.
If you are not part of the conglomerate of poor souls being forced to implement UIs in HTML, you may want to stop reading now and go out to help an old woman cross the street. (Every day a good deed, you know.) So here we go.
Joel's first claim is about standardizing inline editing, which is really a pain nowadays: Gecko (the engine that powers Mozilla, Firefox and their friends) comes with massive support for inline editing, which is used to full capacity by projects like Bitflux Editor. On the other hand Internet Explorer comes with decent editing support as well; it is described on MSDN. But since both implementations differ so much, it is practically impossible to come up with an elegant cross-platform solution. Standards can be such a nice thing sometimes.
Among his other wishes, Joel asks for a way to deliver compressed JavaScript, so that web applications can make heavy use it:
Compiled or compressed JavaScript, so that web applications can use really large amounts of JavaScript with decent performance
This should be possible already using either mod_gzip (for Apache 1.x) or mod_deflate (for Apache 2.x). Both are modules that allow any content (which includes JavaScript files) to be compressed before being delivered to the client. About every modern browser supports GZIP compression and for other HTTP servers similar solutions are probably available as well.
Later Joel claims that there needs to be better event support in JavaScript, in order to e.g. utilize the keyboard in web applications. While keyboard support isn't perfect yet, Google's GMail has some decent support for keystrokes. (Real nerds might whinge that GMail's keyboard shortcuts do not match with the ones from Mutt. But that does not matter here. Really.) So people being interested in at least using some keys in their application may want to take a look at GMail. But be warned: GMail's HTML seems to basically consist of a magic hullabaloo of DHTML and JavaScript, so disassembling something is not that easy.