(The page includes, strangely, one of Peter Kempf's photos of his Rolls Royce Armoured Car Model, as well as a mis-captioned photo of some Rolls Royce armoured cars)
Page includes photos of Holt and Hornsby tractors, the American M1917 tank, the American Liberty Tank, a Schneider CA, a Fiat 3000, a Hotchkiss or CGV armoured car, and a couple of photos of the Renault FT.
Fiddlersgreen are notorious for their approximate scaling. The models are typical FG - easy to put together and approximately accurate. So long as you don't expect too much FG models are quite good - at least they are cheap.
There are builds of most of the models (above) at papermodelers.com. FG is pretty responsive about fixing some of the errors in their models I've noticed.
For the serious nutjob (aka papermodeler) the Polish publishers Modelik and GPM have some WW1 subjects (A7V, St Chamond, Mark IV, Whippet, Rolls Royce A/C) in 1/25.