RFTools RF Monitor
The RF Monitor is a block that you place in the world and that can examine a nearby (currently 3x3x3 area around the monitor) block and give a visual indication of how much RF is left in that block. This block can also give out redstone signals in case the RF in the monitored block is too low or too high. You can use this redstone signal with the Power Relay (see below) to control parts of your RF network. You can craft this block with the following recipe:
Here is how it looks in game:
