This article from PhysOrg says that brown dwarfs may be like light houses, emitting beacons of strong radio pulses. An appropriately advanced civilization might be able to manipulate such an object (if it were within its solar system) to send a “we are here” message, getting a tremendous boost in signal strength from such a natural radio powerhouse.
My first thoughts centered on the use of magnets to deflect the beam, wondering if they could be built to make adequately large deflections in the radio signal to send information to distant stars. A colleague of mine, Dr. Zink, suggested that instead a large net of conducting material could be used to deflect the beam, something where the size of the mesh would be appropriately comparable to the wavelength of the signal. Certainly this net would be much easier to construct, possibly this would not require much more advanced technology than we currently have.
If such a signal house were constructed by aliens, they could do far more with it than send a “we are here” message. They could use it to send messages to ships taking a long slow journey between the stars, or to communicate with a distant colony.
On occaision, SETI does find possible signs of alien life. And they are building more and more powerful radio detectors. If there are aliens, and they make use of such a radio light house, we may be able to see them from very far away indeed.