ROCKLOBSTER, perhaps you'll enjoy seeing the photograph of distant galaxies which cemented the number at ~400
billion:
the Hubble Ultra Deep Field. Astronomers left the Hubble Space Telescope camera open for
ten days. What the image shows is a portion of the sky about the size you'd see by looking through a drinking straw. It shows only two foreground stars in our own Milky Way Galaxy--every other item is a very distant galaxy, including the faintest barely-visible dots of light. Astronomers then extrapolated from this census to arrive at their overall estimate.