Philadelphia mayoral candidates Michael Nutter and Al Taubenberger think you ought to be in pictures - on YouTube, that is.

The candidates have agreed to field citizens' questions during their Oct. 15th forum posted in the form of videos. The event will focus on the candidates' "Visions of a Sustainable Philadelphia," according to organizers from the Next Great City project.

It's a good, meaty topic, and the YouTube approach - patterned after the CNN/YouTube forums for presidential candidates - offers a unique means of exploring the issue.

So what's your question? Well, it should be in step with Next Great City's challenge to the next mayor: to enact "cost-effective policies that enhance environmental quality." As noted by Blaine Bonham of the Pennsylvania Horticultural Society, one of the hosts, the forum will examine "how to make this a more environmentally friendly and sustainable city on a tight budget."

A panel of judges will select the YouTube questions (tagged "Sustainable Philadelphia") used in the forum, but every question will be available online. So this exercise could offer a useful snapshot of city residents' views on ways to keep Billy Penn's "Greene Countrie Towne" green.

It's not far-fetched to imagine that the next mayor might put out his own call for citizen-produced videos on hot issues facing the city. Clicking a mouse button could be one way to put his finger on the city's pulse.