Quiz test
Election Visualiser
Election Methods in Pictures
This interactive visualization illustrates the behaviour of Plurality, Approval, Borda, Condorcet and Hare (Alternative Vote) elections in one dimension, assuming single-peaked preferences. There is also a two-dimensional version that is not interactive (illustrating the absurdities that AV can produce) here.
Political Compass
An interesting website illustrating the nature of two dimensional preferences is here.