Years ago, on the Today Show, a fantastic steak marinade was featured. (Sorry I can't remember who's recipe it is)
Equal parts brown sugar, coffee grounds, and kosher salt.
Mix well and coat steak with dry marinade immediately before grilling.
It's delicious. And it doesn't taste like coffee, so rest at ease you non coffee drinkers. If you trust me, you'll try this. People rave over it.
I most recently used it for our Father's day lunch of steak sandwiches and corn on the cob. It is great for cuts of beef that aren't of the finest sort....New York strip, rib-eyes, etc. I've never had it on a filet, but I'm sure it would be great too!