The nifty, free Unix application 'heyu' lets you easily send X10 commands from the command-lne. It's slick, quick, and fills a very specific need for home automators. I've used it a bit on Mac OS X, and always keep a copy handy for just the right job. I don't use too often, however, but I try to keep an eye on the heyu users discussion group on Yahoo.
Charles Sullivan's message, late last month, said that support for the W800RF32 is coming soon. That's great news, the W800 is a very handy wireless receiver that lets you use security devices and remote controls. You can learn more about the W800, and other ways of using it, in "Hack #78: Know When Your Doors and Windows Are Open" in Smart Home Hacks.
Also, Kris Beazley recently described a concise heyu project for controlling lawn sprinklers. Just the sort of task that you can easily run in the background, without the overhead of a full-blown home automation package. For more on sprinkler control, see the hacks in Chapter 5 of Smart Home Hacks.