Anyone who is familiar with computers tends to know that on the back of most motherboards is a little tower of headphone jacks. This connector (usually 3, sometimes 5 or 6) is a nice way of bundling all the needed analog audio outputs of a computer together, but if you’re salvaging parts from an old or dead motherboard why would you take it? it has a strange footprint, it’s seldom you need 3 outputs from a project, and even less likely that you’d use it to repair another motherboard. Here’s a simple use for it: a headphone splitter. I personally use mine to go from my hardware master volume control to my speakers, wireless headphones, and 5 1/4″ bay speakers. Another mod I did was to take one of these and wire it up so one was pass through, one was mono left and one was mono right. That particular mod was nice for a dual monitor computer with speakers built into each monitor. These connectors usually have leaf switches built into them so the audio path is disconnected and redirected out the jack you just plugged into. The possibilities are not endless, but they’re certainly more than I have stated here. I can post a diagram of the pinout I derived, but you’d be better off with a continuity meter and a 3.5mm plug.
Simple headphone splitter