I really like the looks of cordwood infill. Rob Roy has written a couple books on this method. http://www.amazon.com/Cordwood-Building-...2705&sr=8-1
Supposedly softwood gives the best results. Hardwood checks too much.

The wall in the last photo has wine bottles interspersed for a neat effect...

This might be a way to employ timber cut-offs, too...could just do an interior wall to get the feel of it...