Presets enable rapid switching between different networks. You might use presets for switching between sounds during a performance or experimenting with different ideas within a single patch.
To store a preset, hold the option key and press one of the number keys. To load a preset press one of the number keys. (At some point I'll add more than 10 preset slots.)
Because connections in Audulus fade in/out when connected/disconnected, you can set up your patch so there are no clicks or pops when changing presets.
Also, sharing nodes between presets enables things like delay spillover.
A MIDI program change message will call up a preset, so presets can be used with your MIDI foot controller. This is particularly useful for guitar rigs.