Please go to a Barack Obama public appearance, ask him one of the following questions (derived from a McCain campaign missive [1]), get his response on videotape, and then upload that to Youtube. If you can get a "good" answer from him it would have a devastating impact on his campaign.

"Senator Obama: You got over $100,000 in campaign contributions from Fannie Mae, Freddie Mac, and their employees. Did you ever talk to the executives of Fannie and Freddie about the reckless loans they were giving out? That is, could you please list some approximate dates when you discussed those reckless loans made by your contributors' organizations? I don't need exact dates, but just a few off the top of your head. Just some approximate dates, please."

Or:

"Senator Obama: You got over $100,000 in campaign contributions from Fannie Mae, Freddie Mac, and their employees. Did you ever talk to the executives of Fannie and Freddie about proposals from Senator McCain dealing with stronger oversight of their operations? That is, could you please list some approximate dates when you discussed that proposed stronger oversight with your contributors or their organizations? I don't need exact dates, but just a few off the top of your head. Just some approximate dates, please."

The source for the donations is here and if anyone asks says it's from the "OpenSecrets.org database and various news reports".

The source for McCain's reforms is the "Congressional Record of May 25, 2006 with John McCain's floor speech relating to the 'Federal Housing Enterprise Regulatory Reform Act of 2005'" (link).

Read both of those beforehand and print out several copies of each to give out to interested parties.

For more on my long-running and so far unsuccessful effort to get people to ask Obama tough questions, see this.

[1] From this:

...Bad mortgages were being backed by Fannie Mae and Freddie Mac, and it was only a matter of time before a contagion of unsustainable debt began to spread. This corruption was encouraged by Democrats in Congress, and abetted by Senator Obama... the truth is I was the one who called at the time for tighter restrictions on Fannie Mae and Freddie Mac that could have helped prevent this crisis from happening in the first place... He has received more money from Fannie Mae and Freddie Mac than any other senator in history, with the exception of the chairman of the committee overseeing them. Did he ever talk to the executives at Fannie and Freddie about these reckless loans? Did he ever discuss with them the stronger oversight I proposed? If Senator Obama is such a champion of financial regulation, why didn’t he support these regulations that could have prevented this crisis in the first place? He won't tell you, but you deserve an answer.