For several years now I've been annoyed at my Goldline controller. It doesn't have enough timers, flakey software on the board, various board problems, etc. Recently I installed a Hayward Ecostar motor and a nice man from Hayward updated the software on the board. Nice! Most of my problems with the software went away, but one annoying thing kept bugging me: There aren't enough timers for me to play with and there isn't a good way to interface this to my other home automation projects without spending tons, literally, of money.
So, I built up a RS485 controller and decoded a significant portion of the protocol. I can now control my pool from my laptop. That's only a couple of small steps away from a web interface and whatever the heck else I want to do with it. I used an Arduino as the controller so I can program anything I want into it. I can turn the lights on when it gets dark and then turn them off at anytime I please. Heh, heh.
All of this without spending hundreds on special protocol converters that are almost as hard to interface with as the pool controller itself. In the spirit of this board, I've described the project in annoyingly exhaustive detail under the "Swimming Pool" tab on my blog at http://draythomp.blogspot.com/.
Feel free to grab any of the ideas and code examples and create your very own custom solution too.