Depends on the steak and my mood.
With a really good steak, typically heavy kosher salt and cracked pepper, olive oil. Medium rare, finish with a tablespoon of butter.
If i'm feeling wild, original #7 jack Daniels bbq sauce and for spices I use thyme, rosemary, salt, pepper, red pepper, and i'll grill some red peppers and onions in the same pan to get the same flavor.