My stepmother turned me on to this. If you want a good marinade (especially for tri-tip), use Italian salad dressing. I like Wishbone Robusto Italian because it has big chunks of garlic in it. Let it marinade overnight, then throw on the grill. yum!

Here's one for ribs.

Olive Oil, Vinegar, Soy Sauce, Hoi-Sin Sauce, Garlic. (I do this by eye, so don't ask me for measures)

Marinade for at least a couple of hours.

Pour ribs and marinade into a meat dish, cover with foil and cook in moderate oven for about 45 mins.

Uncover, drain marinade into pan.

Finish ribs on the grill, heat marinade in pan to thicken, pour over ribs.

Another quick and good one:

1/2 cup (approx) Woody's Cook-in Sauce
1 shot Jack Daniel's

Marinate your meat (another good one for tri tip steak) & throw on the grill.

here's a great one for ka-bobs:

For the souvlaki:

2 pounds boneless, skinless meat such as pork, lamb, beef, or chicken
½ cup olive oil
2 lemons, juiced (about 4 tablespoons lemon juice)
¼ cup wine (use whatever you have on hand but red is best)
2 teaspoons dried oregano
1 teaspoon dried thyme
3 cloves garlic, chopped
½ medium onion, chopped
Salt and pepper to taste

For the skewers:

Onions, quartered
Peppers, cut in chunks
Cherry tomatoes

Instructions:

If using bamboo skewers, soak them in water for several hours to prevent them from burning when you cook the meat. Cut the meat into 2 inch cubes. Place in a large re-sealable bag.

Whisk together the olive oil, lemon juice, and wine. Slowly add the oregano, thyme, garlic and onions. Pour into bag and seal. Shake until all the flavors are dispersed.

Store in the refrigerator and marinate for at least two hours or overnight. The longer it marinates the tastier the meat will be. Remove the meat from the bag and discard the marinade.

Skewer the meat, alternating each piece of meat with one of the vegetable choices. Cook the meat evenly on each side until cooked through. Cooking times will vary depending on if you grill it, bake it in a 400 degree oven, or broil it. Serve on a platter garnished with parsley.

forgot the original link in case you want the full article:
http://www.bellaonline.com/articles/art29731.asp