Holt tractor. USA.
When you say half-track, most people (at least those who know what a half-track is) will automatically conjure up the mental image of an M3 or a Hanomag, but in recent years, I've come across some more obscure half-track designs which are interesting enough to bear mention (not least as I am currently scratch-building some ficitious half-tracks).
Acme. 1918. USA.
Tracked vehicles weren't really invented by any one person. The idea had been around a long time before it became commercially viable with the success of the Lombard Steam Log Hauler which was made in New Hampshire in 1901. This machine inspired Benjamin Holt who was already making agricultural machinery and traction engines and in the First World War belt driven Holt tractors (see image at the top of post) were used to haul artillery. The Holt tractors would be the primary inspiration for both the development of agricultural half-tracks (such as the Fordson shown above) and military tracked vehicles.
I'm specifically interested in the wide variety of unusual half-track and wheel configerations which flourished in the first half of the Twentieth Century, not least because half tracks more or less went out of fashion after the second World War and were replaced by more sophisticated, fully tracked vehicles. Below are a few examples of interesting British half-track gun tractors which have caught my eye. I know very little about most of them since half-tracks were apparently not as popular with the general population as tanks so information regarding them is harder to find.
FWD-Roadless. 3-ton half-track.
Morris-Martel Roadless Experimental Half-track.