Jupiter's satellites
This simulation of the 4 Galilean satellites orbiting Jupiter shows how fast the satellites move. Each step is 1 hour. The view is non-inverted, so East is on the left and West on the right. The calculation scheme is given in the excellent book by Jean Meeus: "Astronomical Algorithms", 2nd edition (corrected August 2009), Willmann-Bell Inc. The lower accuracy scheme of the two given in chapter 44 is used. This is accurate enough to show the layout on a given date but not accurate enough to show whether the satellites occult or eclipse each other.
Apart from the colour coding and trails this is what you would see through binoculars (except that as of March 2010 Jupiter is on the far side of the sun - it will be visible again in the autumn). It is possible to photograph the 4 satellites with a simple camera, as described on my home page.
Jupiter has many other satellites but they are all very much fainter than the 4 Galilean ones.