Winders, I'm not sure if your still interested but I normally just drizzle a little olive oil, salt and pepper a Filet Mignon and grill it to rare for myself. I like steak and its natural flavor, that's why I don't marinate them or do a lot of things with them. My favorite is a bone-in ribeye. Oil, salt, pepper and sometimes garlic. 
Sometimes just to do something different, with filet, I'll "stuff" it with Gorganzola or bleu cheese crumbles or Wrap it in bacon.
With filets and other cuts, Spread a little Dijon mustard on it before grilling. This is amazing, but not something I want every time.
Sometimes I'll brush some butter on it, before and during grilling.
D-Ribose is excellent to dust meat with before cooking it, but it's not something most people keep around. I use it for making rubs, but I usually forget to replace what I've used, until I need it again. But, it's something worth trying for sure.
Sautéed mushrooms I most always make with any steak, but they go on the side, not on my steaks. 
That's pretty much it for me, personally. I never do it for myself but I love to make different variations of beef Wellington.
:twocents:
On mushrooms. All mushrooms are editable, but some only once.