I feel the minature filter can be used for shots other than miniatures. It's not even that great at them.
It increases saturation a little, and can give the shot an atmospheric feel. It also helps focus on the subject, while still allowing a wide focal range.
It can also help block out poor textures in a close up, towards the edges of the pic (I.E Ground surfaces/ Walls)
I have more, I suppose i'll post a couple of shots of miniature-filter goodness soon!
Also, two lambo shots have the miniature filter, not one, but the last one specifically uses it to enhance the 'smoky' feel, since the car is spinning it's wheels.