My favorite is to steam them with some w.wine, garlic, basil leaves, dice tomatoe, then dip them in melted butter that was melted w/shredded basil in it.
Mussels brittany is killer too- par-cook them in some w.wine/garlic till they open, quickly cool. Take some softened butter , chopped parley, little lemon juice, chopped garlic, s+p and toss in food processer until mixed. Halve the mussels and fill the shell w/the butter mixture (mussel on bottom) and top w/japanimation crumbs (mix a lil melted butter s+p w/crumbs prior) then broil or cook in oven at 350 till brown. Mussels steamed in coconut milk, ginger, cilantro and either red or green thai curry is also good.