I find numpy too heavy weight for a lot of stuff and also not very good for communication/interchange with other programs. For a lot of my work, I often need to write data files to disk (for C programs to use) or mmap'ed files for concurrent access. In these situations, the fact that array.array offers precise data alignment rules and toString() and toFile() methods that are actually sane, I end up using it instead of numpy.
Of course, if I do significant computations in my python program itself, I just use numpy.
I've been using NumPy for a while now, and I've literally never had a reason to use array.array where NumPy arrays have worked.