About one year ago, I developed a shared widget. Some fraction of my clients refused to load jQuery, as they still preferred older, less popular DOM libraries.
Starting with jQuery's battle-tested event handling code, I trimmed features unnecessary for my widget: event.data, IE7 support, consistent focus events. I replaced jQuery's indispensable descendant selector feature, formerly jQuery.delegate, with a simple conditional in my event handlers. (e.g. Walk parentNode references from event.target, looking for a class name.)
I was left with about 75 lines of code in my DOM abstraction library. I preserved jQuery's tricks for Microsoft's attachEvent and Safari's text nodes. About 15 lines were dedicated to normalizing attributes. My polyfills for preventDefault and stopPropagation were about 10 lines each.
It's amazing how far native DOM has come in recent years.
If you are looking for a standalone event (delegation) library check out one I wrote http://craig.is/riding/gators. The syntax is very similar to jQuery.
Since I code mostly in clojurescript in my home hours any functional idioms from jQuery I no longer use. A long time ago jresig joked about making an oo form of jQuery. It's not that funny now, as it might be slightly easier to wrap an object based lib for all the various compile down to js languages (typescript, coffeescript, clojurescript, scalajs, etc)