The entire living room system, aka the Kids' Home Theatre, is entirely Dark Side: Cambridge Soundworks Ensemble II, Center Channel II, and Surrounds II; Sony Receiver; Samsung LCD and Blu-Ray; Panasonic VHS (yes, the wife has many "classic" Disney VHS tapes); and a Microsoft X-Box 360. After reading this thread, it appears I'm the first to chime in with an X-Box. I use it to stream media from my server. More below.
My bedroom is partial Dark Side: homebrew PC (Quad Core 8400, 8 gigs RAM, 1 TB HDD, NVIDIA GTX 470 1 GB, blu-ray drive) running Windows 7 64 bit and Toslinked to another Sony Receiver, plus Beogram RX 2 with Benny Amina retipped MMC4 and S45-2s. I rip DVDs and Blu-rays on this machine with DVD Fab and cut and paste the contents to my server.
Kids' bedroom is homebrew computer only using a Samsung monitor's built-in speakers and streaming media from the server. Both homebrew computers use the same Zotac motherboard, and I use the built-in NVIDIA soundcard for both. I've auditioned external DACs and have never taken the plunge.
Server is another homebrew running the original Windows Home Server and is based around an old Gigabyte mobo and just a dual core E5200 CPU.
My main system in the dining room has a bit of Dark Side: Samsung iPod dock, iPod Touch 64 GB 3rd Gen, and an Audio Technica preamp for RIAA equalization of the second turntable in that 2 Beogram, 2 Beocord, CD X, BM4000, M70 system.
Out in the garage I have repurposed an NAD 7140 receiver and Klipsch loudspeakers to be amps for my bass guitar and my daughters 3/4 sized Squier. Also out in the garage is a Beosystem.
Serving as a backup to many pieces is one of my favorite all time pieces: an NAD 7175PE receiver. Man what a tank that is. Gathering dust are an NAD tuner and power amplifier, and a Denon preamp.
The Dark Side pieces that get the most use are without a doubt my iPod Touch and the X-box 360 (plus the AV element of the living room system, of course).