I had this idea the other day that could be a brain fart - but would be a relatively easy way to make a hybrid electric pickup truck.
The nugget of inspiration came from a conversion method for big rig trucks ... Concept: Plug-In Hybrid Drive Retrofit for Heavy-Duty Trucks ... Their idea (near as I could tell) was to split the axles at the end of the big rig. There's two drive axles on a big rig, and after the conversion the front of those axles is still driven by the diesel engine while the rearmost axle is driven by an electric motor. Instant hybrid electric big rig. You wouldn't expect it to do a long haul down the highway with the electric, but maneuvering around a parking lot etc could be done on electric power.
My idea was to apply this in a way to a pickup truck. Some pickups have two axles but another way would be to add a second bed to the end of the pickup. The first bed would be the normal drive axle connecting to the gas engine. The second bed would be a second drive axle to which you have an electric motor. It would be a matter of doing some welding, and fortunately trucks usually have a ladder frame under the bed so if you welded those two frames together it should be secure.
Oh, and for a different take on a similar idea ... Otmar has this Stretch project where he welded together two VW Vanagon's to make a long one with dual drive systems (gas and electric).