In this paper, we present a networking perspective of cooperative spectrum sharing in wireless networks. For unlicensed band like WiFi, e.g., 2.4 GHz, it is particularly critical that network nodes share the same spectrum cooperatively and efficiently. We discuss several cooperative techniques for spectrum sharing in wireless networks including strategies to cooperatively reduce the transmitting power, and approaches to cooperatively reduce transmission interference. We also formulate the spectrum sharing problem as a cooperative game. Finally, we conduct extensive experiments to demonstrate techniques and phenomena for cooperative spectrum sharing in wireless networks. In one set of experiments, we demonstrate the wireless broadcast advantage (WBA) by attaching radio modules to cameras, in which automatic photography synchronization is achieved among a group of cameras wirelessly. In another set of experiments, we show that TV band can be shared with commodity network nodes cooperatively.