Although I can understand the use of a motorcycle trike, it would never come to my mind to get one. A motorcycle has two wheels, and because of that, it allows you to split lanes. It means you can get to your destination much quicker, and with much more fun, than 4 and 3 wheel counterparts.
That was until now. Here is a trike I would consider (mind you, I said "consider"). From one of the leading amphibious vehicle manufacturers in the world; Gibbs Technologies .
Gibbs produce a variety of vehicles that are amphibious, in other words, can drive on land, and in the water. All of the vehicles are of the 4 wheel variety, either cars or quads.
But now Gibbs have applied for a patent for an amphibious trike. That means you can ride your motorcycle trike across the twisting roads, through the hills, and when you reach that river, ride into the water, and jetski for a while. Why have more than one toy, if you can combine several passions all in one toy?
Looks like a nice idea for a toy.