I have just uploaded a small video showing my little dam in action, even going underneath to display the redstone circuits and what happens during the on/off operation.
It's my first video and there's no audio as it's all nice and neat.
http://youtu.be/J3T-Uh-jsHY
It can be adapted as a squid farm - they find it difficult to swim against the current, just make sure they spawn regularly at your spot and when you get two or three, close it off and they'll explode and die leaving the ink sac behind for you to collect.
It was a trial and error process for my own learning and there are many things I would do differently. I'd keep it straight and about six blocks in length. If I was really clever I'd have two switches which would operate both ends but with a delay for the opposite so the current will flow properly, that may take some experimentation though. This will provide a current in either direction.
Hope you like it, subscribe to the channel, there will be more videos coming soon.
