What about a new kind of public transport, a kind of blend of taxi and mini-bus? The idea is that customers would call (or register via internet) their intended trip with all details, such as number of passengers and time interval. A central dispatcher center would route its mini-busses to pick up the passengers and bring them to their destinations. The routining problem is logically difficult, of course... but now might be precisely the right time to try out this idea. Thanks to mobile telephones and the internet, customers can communicate their trip requests most conveniently and in sufficient detail. Routing problems of similiar kind were encountered with the recent development of the same cellphone technology, and with postal currier services (privatised rather recently in EU).

Gosh, I have a real buisiness plan. You start in a city (like Paris) with offering transfer services to various middle-sized companies: you would bring their employees from home to work and back, you would bring their clients around, and you would serve them in buisiness trip across the city. That might be an attractive service: the client companies would need less cars to buy and maintain; worry less about gasoline prices; and, in our age of squeezing more efficientcy from workers for (frequently) less pay, they could offer their employees "raise" in the form of a convenient transportation. Effectively, overal transportation costs will be cut by you by moving many client travellers at the same time, and at optimized routes. Hence, there will be plenty room for adjusting service price and your profits.

The second stage would be to offer transfer services to  middle class individuals and their families: they would have a fast and convenient means to travel around the city, for their kids as well (to school and back, etc). The bottom line is to target people and families actually using cars (because the public transport is depictable for them, say), but which would be glad to avoid frequent driving in traffic jams, parking problems and excessive petrol costs.

At these two stages, a basic space-time frame of most frequent routes will be established for you, and you could allow full force of occasional travelers to join. Travelling in your minibus would be a quite cousy experience, with few irritating stops and companion changes. The travel-to-work routine might be made pretty enjoyable: paseengers could watch a flat TV screen behind you back; a wireless internet connection might be available. For the buisiness types which need to call or negotiate while travelling, a comfortable "first-class" half-cabin might be established, etc.

This might be a good way to grow an economically vibrant buisiness of "half-public" transportation. (Hey, can partnerships be made here?!) The service might be very valuable for public good as well: Since the initial target groups are car-using companies and individuals, the service would effectively reduce car traffic in the city, with positive consequences regarding traffic jams and pollution. This means that local politicians should be interested to support you.