Spot.us is one of the very coolest ideas funded via the Knight News Challenge, the funding mechanism that’s supported Global Voices’ Rising Voices project. It’s designed to crowd-fund investigative journalism, first in the Bay Area, and perhaps later in other markets.

Journalists and citizens suggest projects they’d like to see investigated – “tips”. A “pitch” is a reporter’s response to a tip, with a pricetag attached. Interested readers can pledge towards a pitch – if the pledges reach the amount the reporter has attached to the pledge, she’s funded to go report the story.

There’s a small set of pledges and pitches already collected on the site, and they give a good sense for what sorts of stories might get covered: long-term social issues that require a lot of legwork and investigation, as well as creative storytelling. Some tips look like personal axes to grind, but many look like they’d make excellent stories.

My concern with spot.us, which I’ve shared with the founder, David Cohn, is that quality journalism is both a supply and demand problem. Spot.us helps aggregate interest, but it’s unclear whether the ten people who fund a story will represent sufficient demand to get large media outlets to pick up and amplify these creative commons-licensed pieces. Our experience with Global Voices suggests that it’s very, very hard to get media to use your content, even when it’s free. But the local focus may well be the saving grace of the project, and the fact that the project is based in the heavily-wired Bay Area may mean that stories have high impact even if they only appear online.

Everyone interested in journalistic innovation will be watching the project closely – good luck to David and his team.