The pdf http://www.marvell.com/led-lighting/assets/Marvell_88EM8189_IC-01_product_brief.pdf describes a chip that can be used for low power wireless control, and can be powered directly from 120V line voltage. Build a small wireless device (motor control, light dimmer….) Note: this uses zigbee so you’d need to work on both ends of the network.
Perhaps useful for E90, E72 or E15 project.
If you are interested in a wireless project consider using an “electric imp” as the hardware interface. http://electricimp.com/
Design and build a wireless timer for students giving talks. The student tlaking would have an LCD display that counts down the time left in the talk. A green LED could come on at some time as a warning, followed by a red one (and a buzzer?) closer to the end.
The person moderating the talk would have access to the timer through a web page.
The project is not incredibly difficult, but there is a wide variety of tasks (hardware/software/networks…) and the system must be robust and low power.
Build a micropower wireless sensor network. You will need to come up with a scenario where this would be useful.
People might be encouraged to save water if they could see how much they are using. Build an in-line water meter that measures flow – and to make it easier to hook up, have it powered by the flow of water. Can it be wireless too?
If you want to do a project with wireless communication and don’t mind writing the communications software at a low level (or want to learn how to do this) check out the development system from TI. Note: this is much less capable than something like wifi, but much lower power (both Watts and processing power).