In the first couple of years of XML, I remember having discussions with people like Steve Ball and Paul Prescod about a hypothetical beast we called "behaviour sheets". The idea was that, just like stylesheets associate a style with particular elements or patterns of elements, a "behaviour sheet" associates behaviour (e.g. what to do when clicked on or moused over or dragged) with particular elements or patterns of elements.
Netscape submitted a spec to the W3C, although they called them Action Sheets.
Well, the idea (and an implementation) has emerged again in the form of a Javascript library called Behaviour. Ben's a Kiwi so he spells it correctly too! :-)