I think I would like some kind of virtual experience where I have my own Memory Palace, the method of loci, the visual virtual space in your head where you walk through as you recall things. But not just for recall, for construction too. I would invite other people in and they help me build it and I help on theirs too, we build them together.
Some kind of mashup at the intersection of hypermedia systems like HyperCard, MOOs like LambdaMOO, commonplace books, blogs, microblogs, personal wikis.
I wonder if this is some terrain where Spritely is going? That would be rad.