Wandering Aramean writes a Boarding Area blog and also has created a suite of tools that can be used for free by anyone. One I just saw (thanks Million Mile Secrets) is his Avios Map.

The Avios Map works like this:

Type in any airport in the world.
The map shows all the airports you can fly to directly for 4.5k, 7.5k, 10k, and 12.5k Avios in economy.

You can use the map to see where you can go from your home airport for what price.