In the above picture sodium and chloride are put together.  Notice how
that extra electron in the sodium (shown in red) transfers over to the
chlorine atom.  This makes the sodium atom an ion with a positive
charge (shown with a +) and the chlorine atom an ion with a negative
charge (shown with a -).  This attraction of the two ions (+ and -) draw
the atoms together and bond them.  (Duh......ionic bond)
Ionic Bonds - The bonding
A Video on Ionic Bonds, divided into two parts for ease of playing.  
Requires a broadband connection.
Lithium Fluoride is another common ionic compound, move your
mouse over the image to see how the electron in the outer
lithium shell moves to the Fluorine.
Notice that the extra electron in the Lithium is transfered to the Fluorine