Residential broadband consumption is growing rapidly, increasing the gap between Internet service provider (ISP) costs and revenues. Meanwhile, proliferation of Internet-enabled devices is congesting access networks, degrading end-user experience, and affecting content provider monetization. In this paper, we propose a new model whereby the content provider explicitly signals fast- and slow-lane requirements to the ISP on a per-flow basis, using open APIs supported through software defined networking (SDN). Our first contribution is to develop an architecture that supports this model, presenting arguments on why this benefits consumers (better user experience), ISPs (two-sided revenue), and content providers (fine-grained control over peering arrangement). Our second contribution is to evaluate our proposal using a real trace of over 10 million flows to show that video flow quality degradation can be nearly eliminated by the use of dynamic fast-lanes, and web-page load times can be hugely improved by the use of slow-lanes for bulk transfers. Our third contribution is to develop a fully functional prototype of our system using open-source SDN components (Openflow switches and POX controller modules) and instrumented video/file-transfer servers to demonstrate the feasibility and performance benefits of our approach. Our proposal is a first step towards the long-term goal of realizing open and agile access network service quality management that is acceptable to users, ISPs, and content providers alike.