I looked on google and found numerous options for "locking" hdmi cables. Blue Echo has an interesting product, where a connector attaches to the hdmi port.
What is anyone else using?

Here are some links I found.
Locking HDMI Cables and Connectors — Reviews and News from Audioholics (http://www.audioholics.com/education/cables/locking-hdmi-cables-connectors)

Perfect Path High Speed Locking HDMI Cable with Perfect Lock Connectors and Ethernet Channel - High-End High-Performance HDMI Cable with Connectors That Lock - Supports 3D and Ultra-High Resolutions - 25 Foot (http://www.google.com/products/catalog?hl=en&cp=23&gs_id=1w&xhr=t&q=locking+hdmi+connectors&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=989&bih=484&wrapid=tljp1323538608906044&um=1&ie=UTF-8&tbm=shop&cid=10195330983932983743&sa=X&ei=rZjjTomhG8bAtgf1yJCHBA&sqi=2&ved=0CIkBEPMCMAE#)

hd EZ lock Universal HDMI Lock hd EZ lock Universal Locking HDMI Cable Adapter hd-ez-lock (http://www.blueechosolutions.com/proddetail.php?prod=hd-ez-lock)

Bruce Yarock