Marjoram is good for most anything oregano is good for.
One thing i like it in is a Mexican dish, I just know as "rajas" (means rags) made out of poblano peppers. basically grill or broil poblano chiles until their skin blisters and comes off the chile meat but not too long. Flip them a few times so they are evenly done, rinse under cold water and remove seeds stems and skins. then chop the chiles lengthwise into rags. sautee an onion, mushrooms and garlic, add the poblanos and marjoram, then simmer in some stock until it evaporates. I finish with cream and some white oaxaca cheese, but you can do without dairy too. serve as tacos or on meat.