Demoscene is a long form example and proof of concept desktop application built using netidx. It is a clone of the essential (to me) features of Rhythmbox.
In it's current form it clones the browse and search modes of Rhythmbox. There are no explicit playlists, but dynamic ones are constructed by entering a search filter, and mutli selecting artists and albums.
Being simply a netidx publisher it is usable from the command line, and programatically over the network via the netidx api, however it also includes a default graphical view designed in and for the netidx browser.
The user can customize this view as desired.
This is an experiment, and a proof of concept. I can't honestly say I know where it's going to go. Clearly it's possible to build rich graphical interfaces using netidx. Whether it's desireable or not? Well, in my humble and biased opinion building this one went pretty well, but I don't know if that's down to the example I picked.