This month's idea comes from Google Ventures general partner Karim Faris:
"When driving around a city looking for parking, I find it so frustrating to pass big, empty lots with tow away signs. Why not launch a marketplace? Provide urban businesses and individuals who own real estate the opportunity to monetize their space off-hours. People will pay."
Got an idea you're not using? Send it to freeideas at fastcompany dot com and you might see it here next month.
[Image: Flickr user Tim Lenz]