The Pallet Truss...
Chris Magwood's book 'Making Better Buildings'
includes a section on using pallets for making roof trusses.
The pallet truss was developed by architect Alfred von Bachmayer
who first used them to build affordable housing in Mexico.
After several prototypes Alfred developed a simple
way to construct structurally sound trusses. His truss design was
modelled in a computer to identify the required number of nails
for each joint. Glue at each joint gave the extra capability
needed nailing from both sides to tighten the joints.
Pallet trusses can be made to span distances for
both floors and roofs. More generally 'Making Better Buildings'
gives a thorough overview of wooden trusses, their environmental
impact, durability, cost, hours and skill required to make them.