OH heck yeah! I melt the butter with a little salt and baste the steaks right when they come off the grill. Let 'em rest for 4-5 min. Mmmmmm. Now I'm hungry.
If you cook the steaks in a pan (or even if you just pan sear them), you can use butter in the last minute or so and then make amazing pan sauces from what's in the pan after removing the steaks.