Categories of OPAC improvement options

The Disruptive Technology Jester has written a short piece entitled Schemes to Add Functionality to the Web OPAC.  The article outlines the four basic types of OPAC improvements: enhancements, wrappers, replacements, and full on ILS replacements.  These categories kind of float around in our heads but it is nice to see them outlined clearly.  I have seen a lot of articles that discuss OPAC improvement options.  It would be helpful if someone used these categories and then created a full list of all the different options available to libraries in each category.  I am sure someone will do it.  Sadly, that someone will not be me.  I'm just too tired.  Sorry :)