Over-the-air programming (OAP) is a fundamental service in sensor networks that relies upon reliable broadcast for efficient dissemination. As such, existing OAP protocols become decidedly inefficient (with respect to energy, communication or delay) in unreliable broadcast environments, such as those with relatively high node density or noise. In this paper, we consider OAP approaches based on rateless codes, which significantly improve OAP in such environments by drastically reducing the need for packet rebroadcasting. We thus design and implement two rateless OAP protocols, rateless Deluge and ACKless Deluge, both of which replace the data transfer mechanism of the established OAP Deluge protocol with rateless analogs. Experiments with Tmote Sky motes on single-hop networks with packet loss rates of 7% show these protocols to save significantly in communication over regular Deluge (roughly 15-30% savings in the data plane, and 50-80% in the control plane), and multi-hop experiments reveal similar trends. Simulations further shows that our new protocols scale better than standard Deluge (in terms of communication and energy) to high network density. TinyOS code for our implementation can be found at http://nislab.bu.edu.