Instituto Federal Electoral (Mexico)
it also has links to the state electoral institutes for state election data

Detailed U.S. Congressional and Presidential Elections Results since 1920 provided by the office of the U.S. House Clerk

David Leip's Atlas of U.S. Presidential Election Results

A great worldwide directory at Elections Resources on the Internet/ Recursos electorales en la Internet
by Manuel Álvarez-Rivera

            Including explanatory pages on:    Australia
                                                              Spain
                                                              Canada

Australian Electoral Comission or Adam Carr's Australian Elections Archive will tell you all you want to - and don't want to - know about Australian elections 

Election Comission of India runs the greatest electoral exercise in the world

UK Election Comission has recent elections data
For historical UK data - and lots of great trivia! - check out David Boothroyd's United Kingdom Election Results

A lot of the info (in Spanish) on electoral systems around the world can be found at the ACE Project site 

Lijphart Elections Archive at the UCSD

International Institute for Democracy and Electoral Assistance (IDEA) has the worldwide data on voter turnout since 1945

And, finally, last but not the least, THE OFICIAL MONSTER RAVING LOONY PARTY
                   Vote for insanity: You know it makes sense!