Automatic graphic file conversion (OS X)

There's a great command-line tool  for graphic file conversion called sips. For example, to convert all BMP files in the current directory to PNG files placed in a subdirectory you have made called 'pngs', just type:

sips -s format png ./*.bmp --out pngs

Of course, for 1-2 files, using Preview is probably just as quick, but for 10+ files, this can save a lot of time. I think imagemagick can do something similar on Linux, not sure about Windows.

UPDATE: In Linux, use e.g.

mogrify -format png *.jpg