Viewing missing methods/software, part II

It appears the strategy of using Google Maps with YUI display of items to add to the map will basically work. Rather than doing drag and drop between YUI datatables, I'm using just the drag and drop YUI code on a list of options, each with the possibility of limiting it to one item (for example, one can first organize by optimality criterion, deciding to show all or just likelihood). The interface is based on the YUI example, but with just one list, with one element of a different color so that options placed above this element appear on the tree while ones below do not (inspired by "the line" on Google Summer of Code's mentorship application). I originally thought of having two lists side by side, allowing people to move elements from one list to the other, but this was too wide for some screens once the possibility of options selection was added. 

I've also gotten a plain white Google Map (to replace traditional geographic maps) working, as well as overlays. Google maps have a wrapper for XmlHttpRequest called GXmlHttp that should make refreshing the chart based on user-sorted options possible. Now the question is how to efficiently recover information from the database to draw the tree, highlighting which branches lead to software+methods, just methods, or nothing.