Moving all those fun JavaScripty (er, EcmaScript?y) attributes like onmouseover and whatnot to CascadingStyleSheets. You then write the EcmaScript? handlers right in the style sheet. Pretty whacky, but that's why it's only a proposal. Oddly enough, it's being made by MicrosoftCorporation and NetScape.
Looks like the original proposal has mutated or died. You can achieve a similar sort of effect (scripts as a style) by having your Javascript locate the elements to animate by class instead of by name (or, worse, with online Javascript). See AsynchronousWidgets.