Korean grilled tongue is wonderful. I also had a wonderful tongue taco in LA, at a place that also served brain tacos, whose texture is too much like a cross between fat and cartilage. But the tongue sandwich I had at a NY deli was awful - but then I don't know if I've ever seen good food at a NY-style deli.

I'm not sure if tongue should count as an "organ" meat since it is a muscle. I also tend not to count invertebrates since their anatomy is so different that it doesn't matter to me that we only eat the urchins' gonads.

One thing that's a lot of fun is fish eyeballs. Most Asian restaurants will cook and serve you the entire fish, and my spouse and I get one each.