Many of the X10 modules are available at RadioShack, but are re-branded as Plug'n Power. They also have a alarm clock you can use to time events (if you don't want to use a computer).
RadioShack also has an alarm system compatible with Plug'n Power (X10). It has remote controled window, door, motion and etc. sensors... the nice part is that it's wireless.
It is worth noting that there is a difference between lamp modules and appliance modules. Lamp modules are nice because they are silent and offer dim capabilities. However they lack the wattage to handle florsecent lights, and other high wattage devices.
If you have an aquarium with live plants, you will find having timed lighting a real convience.