Spottinground has a photo tutorial on making barbed wire bases.
barbed wire
Modeling Barbed Wire
The 20th Century Wargames blog has a great photo tutorial on making trench wire
Miles Of Barbed Wire
Tim’s Wargaming Blog has a photo tutorial on making “36 Miles of Barbed Wire.”
Making Barbed Wire For 6mm Scale Figures
The Wargaming Site Blog has a nice photo tutorial on making barbed wire emplacements for 6mm wargames figures.
Making 15mm Barbed Wire
The League of Ordinary Gamers has a quick and easy idea for making some good looking 15mm barbed wire.