From an e-mail from Russ Feingold:
"Pick a Progressive Patriot" is your chance to vote for whom we will support with early financial help, giving them the ability to build strong grassroots programs that will enable them to be successful on Election Day.
Our latest installment of "Pick a Progressive Patriot" will end next Monday at 5 PM central time. If you aren't familiar with these great candidates, you can learn more about them on our Meet the Candidates page.
Whichever candidate receives the most votes will receive a $5,000 contribution from the Progressive Patriots Fund for their 2008 election. You can vote for your favorite Senate challenger here.
UPDATE: You can apparently vote more than once, over a period of time. I voted a couple of days ago and I voted again today!