I was just about to post this thread myself, and, happily, the forum does the search for me. :-)

I too am interested in this topic, but like most people, hadn't done the math about available power at the headset jack vs efficiency of IR LEDs.

It *sounds* as if someone upthread did, but they didn't show their work, so I'm still not sure.

For a little more space, I would assume you could build a squeeze-on dongle with a 2016 coin battery and an SMC driver transistor to bump up the power from the headset jack, I suppose, though we're getting into 'fabrication' territory.

What was that "you come up with an open-design widget and we'll build it for you" website/company mentioned on Slashdot last week?