As mobile hand-held devices such as cell phones and personal digital assistants are battery operated, it is important to minimize their energy consumption. The limited lifetime of the battery is always a problem for all portable devices. Although battery technology has undergone a massive development over the years, it has not kept pace with other technologies. Therefore, research needs to be done to use the limited life time of the battery in an efficient way. With developments in science and technology, the power consumption of portable devices has been brought down due to the decrease in the size of the display and optimization of components. The trend toward smaller sizes of portable devices involved is responsible for the wireless network interface consuming a larger share of overall power consumption of a system. In order to optimize the power consumption of wireless communication, we should be aware of the power consumption pattern. Accurate energy models are required for designing and testing energy aware protocols. The accuracy of these energy models and their contribution toward energy aware protocol design depend on the accuracy and availability of sufficient data about power consumption of these devices. This work contributes to the building of such a power consumption database through a series of measurements of currently available Wireless Network Interface Cards (WNIC) and Radio Frequency Identification Devices (RFID). These measurements also help in understanding the behavior of these technologies at the lower levels of the network stack.