I like having steak plain (although yes, definitely with some salt and pepper) well enough, but it's way more fun experimenting with various spices, herbs and other flavourings. I'm definitely a herbs person at heart - basil and oregano is great with any meat, tarragon and salvia can do wonders to pork and chicken, and marjoram and rosemary rubbed on a lamb roast is probably somewhat similar to heaven. Chili and coriander can be a great combination, especially for chicken. If I'm barbecuing or roasting the meat, I often make a rub (I don't know if it's still the correct term in this case) including sweeteners or condiments - honey, syrup, chocolate, soy sauce, mustard, steak sauce, oil, what have you.

I also put garlic on pretty much everything.