RE: Now, THIS is cool!
Yes there are several devices and technologies in the market for this.
The simplest and least expensive, is a loud buzzer that goes off when you turn off your TX or the plane looses reception.
If the plane is buried in the bush, the audio permits you to locate it, but you must be within hearing range.
More sophisticated systems are also availlable.
One uses a radio direction finder and a small plane mounted transmitter.
These have a range of up to 1-2 miles at best.
Surpassing that are systems where the plane reports it's GPS position via cellular networks... much like having a GPS enabled cell phone within the plane that is constantly reporting it's position.
Such devices pinpoint a plane almost instantly and act to record flight movements.
If I recall correctly I believe Eagle-Tree has such a device.