Plotting Flight Routes Flying Overhead

Anyone know of a way to get a list of which aircraft are due to fly overhead a certain location?

If you click on any radar object, there's an option to show the projected route, based on the filed flight plan.

I would like to figure out a way to feed all filed flight plans and decipher which are flying over a certain location/set of co-ordinates.

I'm sure there must be a program written for this already somewhere...hopefully someone can help!

Cheers