Now that Democrats have won a congressional majority in 2006 and are dominating the polls in 2008, you hear very little from the election fraud hysteria crowd, as pointed out in this post.
The conspiracy theorists arose from the presidential election of 2000. They pushed for the elimination of punch card systems and ushered in a bunch of electronic voting systems, which were in place as Republicans won elections in 2002 and 2004. The cries of foul over the electronic voting systems reached a high pitch prior to the 2006 and then died when results showed Democratic victories.
One group has been hounding a client (DuPage County Election Commission) for several years, making all kinds of wild, baseless accusations about election fraud. Don't know what the group will say now that Democrats outnumbered Republicans in Tuesday's primary, and most of the GOP establishment's candidates lost. If Republicans are rigging elections in DuPage County, they are doing a very poor job.