Well, apparently the Huygens probe that landed on Titan a few months ago is still active. Scientists are going to try to receive it's (possibly last) faint signals by calling in the general audience.
This friday, everybody is requested to go outside between 12:30 and 13:00 and aim their cellphones east to catch the signals. Cellphones are sensitive to the radio signals emitted by the probe.
It fooled me for a second, then I realised friday is April 1st...