Democrats have plenty to worry about over the next five weeks, but it nonetheless behooves Dems to get up to speed on the latest voter suppression scams. In that regard, Demos and Common Cause have partnered to present a must-read report on the topic, “Voting in 2010: Ten Swing States: Problematic election laws and policies in ten swing states could impact enough voters to determine election outcomes.” (PDF Executive Summary here)
The report profiles ten states (AZ, KY, CO, IL, LA, MI, MO, NV, NC and OH), where close elections are expected. The report focuses on laws and policies built into the structure of state election codes, rather than the illegal suppression practices that popped up in FL and OH during recent presidential elections.
The fact sheet on Kentucky, for example, reveals the obstacles Democratic candidates face in that state, including cutting off registration 28 days before the election, draconian felon disenfranchisement disqualifying 24 percent of African Americans, no legal mandate to disseminate voter information and a poor record of complying with the legal requirement to register people at public assistance agencies.
The report also credits each state for “exemplary voting laws” where applicable.
There are also reports of a voter caging operation underway in Wisconsin. According to Karoli’s post, “Voter Suppression in Wisconsin, Courtesy of the GOP and Americans for Prosperity” at CrooksandLiars.com,

Here’s how it works: A mailer is sent to registered voters. Any mailers returned by the post office are put in a database and those voters are submitted to be purged from voting rolls. Of course, the targets are never Republican voters. They’re Democrats, and generally minority voters in particular….One Wisconsin Now has uncovered this plot with evidence, but don’t assume this is limited to Wisconsin. I guarantee you it isn’t. They are targeting as many states as they can, but particularly swing states. Expect Ohio, Pennsylvania, Nevada, Colorado, Arizona just to name a few to have the exact same operations afoot.

And here’s a recent report on voter suppression in Texas.
In addition to the aforementioned laws and policies, and ‘caging,’ Dems should be ready for other suppression practices, like switching poll places, intimidation, parking obstruction, misleading and incorrect poll information, inferior computer equipment at polls in minority neighborhood polling places,
Stephen Ansolabehere and Eitan Hersh also have a contribution to the topic in their “Early and Often” post at the Boston Review, in which they note,

Registration problems create barriers to voting and make it difficult for administrators to communicate with voters, identify voters at the polls, and audit elections after the fact. Reforms following the 2000 election sought to improve the accuracy and currency of the voter-registration lists. Most important, all states now have statewide voter files. So how good are the files today?…
This summer the Institute for Quantitative Social Sciences at Harvard University and the Caltech/MIT Voting Technology Project issued the first comprehensive, nationwide analysis of the quality of information stored on voter registration lists…Nationwide, approximately 1 in 16 entries on the registration lists is unmailable. The magnitude of the problem varies greatly throughout the country. In California, Massachusetts, and Washington, D.C., about 1 in 50 entries is problematic, but in Arkansas, that number is 1 in 5.

The authors provide a chart ranking every state. This is not just about incompetence and sloppy registration management. The states are all well-aware of their rankings and the reasons for it, and in most cases it’s a matter of political manipulation — almost always to the detriment of Democrats.