Here's a very nice simple teriyaki marinade:
1/3 cup each - soy sauce, cheap cooking sherry, and peanut oil. 1 T. each minced garlic and grated fresh ginger. Make it 24 hr. ahead of use, and strain out the chunks.
You can reserve some of this for use as a baste, and you can add some molasses to the baste to make it caramelize (this is good!).
I marinate chunks of chicken and skewer with pineapple.