Speaking on the phone to my brother, I told him about the Listy Thing I've been working on, he pointed me to workflowy. It's an outline/list todo thing that already does a big chunk of what I had in mind for Listy Thing (quite funny they've also got a 'y' on the end). The UI is awesome, which on the one hand is inspiring in demonstrating feasibility, on the other scary, showing how far I have to go.
It is basically what I'm after, only I want something backed by RDF so that more data can be associated with nodes (especially nodes which correspond to Web resources), the data can be reused, and many alternate views are possible.
I'm still a little stuck on the fundamental question of how best to represent lists, I guess I just have to try things out. Had some good suggestions on the G+ page - there's even an Ordered List Ontology.
The issue's a bit conflicted, because on the one hand useful ordering is generally tied to some particular property (e.g. dc:date) so the list structure can be generated on demand (via SPARQL or whatever), no additional ordering is needed in the data. But then as far as user experience is concerned, as a list is being put together the order can be totally arbitrary - i.e. there is an order, only we're not quite sure what it is yet. This might suggest using rdf:List as a general purpose mechanism.
I think I'll try some kind of low-cost property (with a numeric value). So a property, which after all is just another kind of resource, gets minted when the list is created in the UI. Ideally I suppose it'd be a bnode but a quasi-disposable URI will do. Dunno, give it an rdfs:label on the fly and associate it with user/date of creation?
I use the namespace http://purl.org/stuff# for "disposable" classes and properties (feel free to follow suit). They're Cool URIs in the sense that they'll always resolve (although I must add RDF docs to that URI), disposable in the sense that they appear in instance data but won't have any more definition.