Well, this isn't about automation per se, but I consider it one aspect, especially when expanded to included multiple receivers and emitters. I built the circuit into a Penguin Mint tin, with jacks for power, receiver in, and emitter out. The receiver and emitter both terminate to 1/8" plugs.
I used the circuit found on this page, and added a 5-volt regulator and some slightly different cap and resistor values to match what I had available. I used a (Sharp) receiver module I purchased from AllElectronics about a year and a half ago, and a stick-on emitter I got in the same order (I couldn't find either one for sale in a recent search). I'll try to remember to take some pictures of the whole setup -- my DVD player and VCR are hidden inside a modified old suitcase, and the emitter is in there with them. It's worked very well so far, with no issues.