getting this in at the last minute for the contest!
I use x10 in two ways. one is for my home automation, and the other is for a website i run called ferretcam.org
as for my home automation setup I use a cm15a hooked up to a laptop on a table in the livingroom. the laptop acts as a picture frame/caller ID and is very quiet. I run activehome pro, BVC, and PCC (using VW Kate TTS voice). I have 5 learning remotes, 4 palmpads, two slim wall switches, seven lamp modules, two security cameras, 5 motion sensors, and a few macros for scene lighting. obviously the system is voice controlled, though only in the room the laptop is in. the learning remotes work great with my TV and HTPC which runs BeyondTV (5 tuners 2TB storage)
As for the ferretcam.org system. that uses a firecracker interface, a cm11a interface hooked to a xvideo10 video switcher, and a base transceiver. with a cgi script that i put together, 4 cameras, a universal module and an appliance module.
I stream live video of my ferrets to my website using flash media encoder 3 and justin.tv. there are 4 non x10 cameras wired to the Xvideo10 switcher. from the site you can click to switch cameras, turn a fan on and off, and dispense a treat to the ferrets.
when you press the button to dispense a treat the cgi script sends the command through perl to a command line exe which fires the cm17a firecracker. that gets picked up by the base transceiver which passes it along over the powerline to the cm11a interface, which sends the command over the serial port to the Xvideo10 switcher, which of course switches between cameras.
for the treat dispenser I use a universal module wired to a digital fish feeder's manual feed button. it is attached to the top of the cage so treats(healthy food) fall into food bowls. the chime feature (with muffling) alerts the ferrets that a treat is coming!
the fan is a cheap walmart 3" fan hooked to a standard appliance module.
The hardest part (beside the cost. lol) was allowing people to control it over the internet. I didn't want people to be able to screw with my home automation stuff, so the script had to have security. I asked Scott Creiver if I could start with his script which did what I wanted but talked with the cm11a using buggy activehome .dlls and only worked well on win95. with some editing and a command line exe for the firecracker, I got something working for winxp and the cm17a with no activehome hacks. theres a link to the script on the site.
I've been using x10 for home automation for about 15yrs, but started the ferretcam project about 3yrs ago. wherever I moved to the first thing I would do is setup x10.
I probably missed a bunch of things so ask questions! also I'll update at the bottom of this post if I think of anything else.