Solar 1000 Controller
This has to be one of the coolest things you can get for an
aquarium. It's the automation super component. It dims Flouresent
lights based upon time plus controls powerheads, timers, and moonlights.
All of this is based upon the day of the year, the season, simulated
storms, and many other factors. They are a bit expensive, but I got
this one for a steal from an online ad.
IceCap 660 Electonic Ballast
I got this in the same online ad as the Solar 1000. It can control
440W of VHO tubes. Plus they are 100 percent dimmable. You do have
to add some extra grounding capabilities to your hood design, but
it works great.