I had a great recipe for marinated heart, but my ex made off with it...now, that hurt. I cut it into strips, marinate it in nearly anything (usually olive or sesame oil, sherry, soy, some fresh garlic or ginger if I'm feeling ambitious) and either saute it or grill it. It's important not to overcook. Some are put off by the texture, but nearly all praise the taste.
For liver I follow the bacon and onions route. It always feels a little more like something I should do than something I really enjoy. It would be great to work out a truly good pate.
FWIW, I really like deer kidneys and fully intend to try a tongue...I'm just in such a groove on cleaning or quartering I keep forgetting to take one.