I came to see about an open source firmware for wifi routers last week. The main advantage of this firmware is, you can install this firmware to your favorite routers like linksys, broadcom routers etc. I had a try on this to my Linksys WRT54G router. This is not only a firmware for a router you can even manage the data usage to each and every clients that are connected with this router using a Web UI provided with the firmware. The Web UI has the inbuilt facility manage different clients with help of Web UI.You can mark the clients in the map available with firmware. It uses google maps for this.
Download your device specific firmware and configure it. Control your clients data usage. We can deploy this in areas like hotels, public parks, chill out place etc. Design your data plan and resell it to your customers!!!!