On several blogs the idea of having a rich java script passed, for example on ZefHemel.com: Rich Web UI: Search As You Type
I guess it would be time to extend HTML itself with a more advanced script; java like preferably although then directly supported by the browser, and less aimed at custom drawing but using an API provided by the browser.
I’m currently experimenting with Microsoft .net assemblies which are downloaded in slimmed form as webpage which are executed with very limited access. Which works neat although it is still an overkill (a .dll is about 20 Kb, even if you got only one line of code..)
Just a thought.