Depending on what the board is for, you could use 'Panelvent'. It provides racking strength for a timber frame, it is also breathable (ie lets moisture move through it), and the board is held together by natural lignins. The board is created through a process where the the wood fibres are compressed under great pressure, the pressure is momentarily released causing the wood fibres to expand and split - releasing the natural lignins, the fibres are then compressed again forming the board.

Its a nice material to work with as you don't have the same worries that you would have with synthetic glue soaked sawdust in your hair and clothes and air you breath, while working. I think it may contain very low levels of formaldehyde....but worth looking into.

I would be surprised if there weren't other glue free boards out there as well.