Hey there,
I want to hook up a central Arduino to some other Arduino nodes, and I'm wondering if you can send bytes or any number values over the digital pins, as you would a serial. Ideally I want 9 nodes, so I can only use one digital out from the central Arduino. Hmmmmmmmmmm
You can use the software serial package but better is to implement an I2C interface with one arduino being the master and the others being slaves.
There are examples of this in the IDE itself.
Perhaps you should read through this guide before trying to reinvent the wheel...