If you want to learn more about Cynthia McKinney, there is no better introduction than the documentary 'American Blackout', which chronicles the voter disenfranchisement of 2000/2004 and the successful Republican effort to unseat Cynthia McKinney in 2002.
This is the trailer for 'American Blackout'
Here is a bit of the film describing black voter disenfranchisement featuring everyones favourite honest politician Tom Delay.
I'm sure that you will enjoy these clips and be moved to action as many others were too.
Take a trip to http://www.americanblackout.org and pick up a copy of the full film.