I guess it will kind of boil down to applications. And a way to advertise them to everyone else who has access to the network.
Here are some random ideas Make a mirror of mods.dk or something like it, are their any unlimited mod sites? As far as I know you can only lookup one per day.
How about a part-number datasheet lookup service? Or periodical lookup.
Or hosting services for ham software development projects.
For a good place to start how about someone setup a listserver on the amprnet, perhaps "ampr-services"?
It would probably be a good idea if there was a way for the HSMM nodes to have a way to tunnel to other remote nodes. Maybe touch base with the firmware developers?