by Engineering faculty at the Universite Laval in Quebec, Canada.

http://www.gel.ulaval.ca/~busque00
/elec/main_e.html

An electric charge simulator allows viewers to place charges of selected signs and sizes on a map, and then to draw in electric field lines by clicking at various locations on the map. It is possible to create a plot of electric fields resulting from simple charge arrangements. We advise you read the brief explanation before using the applet.