PartyNexus is a sync hub for PartyHall. Your appliance will automatically sync pictures taken to it and provide a neat interface to share it with the people that were at the event without relying on zip export file.
While not strictly required, it is really recommended.
It's also mandatory if you want to use the karaoke feature (It can be ran on your own computer if you want to use it for this purpose only).
PartyNexus is still in early development and not available to try out.
Note that is not compatible with any currently released PartyHall (which includes v0.74 to this day). It requires PartyHall 2.0 minimum which is a fully rewritten version of PartyHall.