I've been using an Exa too lately:

exa by berangberang, on Flickr

I've run about five rolls through it this summer, but haven't developed them yet so I don't really know if it has been a success. But it is rather small, rather quiet, and you can shoot "from the hip" without losing the ability to compose your shot, thanks to the WLF.
It is also rather friendly looking and sometimes people ask you about it.