Widespread Dirty tricks in Florida and Destruction of Democratic Voter Registration Forms in several states;  there were similar dirty tricks in Ohio, etc. 

 (& maybe a few vice versa)

This is just a small sampling of articles covering this and doesn’t include cases in many states where it occurred. There was also widespread manipulation of absentee votes which isn’t covered here but affected a very large number of votes.

http://www.google.com/search?num=100&hl=en&lr=&newwindow=1&q=democrat+registrations+destroyed&btnG=Search (links to hundreds of articles)

http://www.klas-tv.com/Global/story.asp?S=2421595&nav=168XRvNe

http://www.dailykos.com/story/2004/10/12/204449/72

http://www.truthout.org/docs_04/101504A.shtml

www.frykitty.com/mtarchives/003373.php (Oregon)

http://www.portland.indymedia.org/en/2004/10/299740.shtml

etc. etc.

http://www.flcv.com/dirtytrf.html

http://www.flcv.com/ussumall.html