Don't know if this is exactly what you mean, but in Slovenia, there is this website called http://prevoz.org http://prevoz.org (which translates to "ride.org"),

Don't know if this is exactly what you mean, but in Slovenia, there is this website called http://prevoz.org http://prevoz.org (which translates to "ride.org"), where users/drivers can post when and where they're going, and others can contact and ride with them. It's worked remarkably well for the past 5+ years and right now, there are almost 500 rides available for today.