Peanut butter - if they like it. It's so sticky, sort of prevents the wallering around in the mouth discrimination thing.
My mixed breed dog will eat anything I hand him, which makes medication administration a breeze. If I need to trick him into something I use cat food. Cat food is a rare and special treat - only because I won't let him eat it I guess.
I didn't think about using cat food, that's an idea...thanks. My dog, while he hates canned dog food or anything with gravy in it, keeps stealing the cat's canned food, no matter how high I put it up, he always manages to get the bowl down somehow. I'd probably have to put the medicine in the food processor to chop it up really fine though, or he'd still spit it out.