Most gratuitous use of an Arduino

So, a while ago, i built a circuit to shut off our aquarium water filter when the bucket gets full (http://mhkaufman.blogspot.com/2010/01/rodi-auto-shutoff.html). About a month ago, my room mate managed to break it. So rather than going through the "hassle" of rebuilding it, I decided to take the easy way out and replace the whole thing with an arduino. All it does it does is open a solenoid valve and start power flowing to one pin. When it sees current in the other pin (which happens when both pins hit the surface of the water), it shuts the solenoid valve and stops power to the first pin. The only even slight improvement over the original non-arduino version is that once this version shuts off, it doesn't pass any more current through the water, which is nice because it limits the electricity-aided dissolution of metals from the probes into the water, which can be bad for the fish. It even looks exactly the same, a black box with a button and one blinking LED on it.