Few things set a cook's heart afire as quickly as a really kick-ass display of finfish, crustaceans, and mollusks. The colors alone take one aback: deep ruby tuna steaks; pink, opalescent whole snapper; silvery-patterned striped bass; ivory diver scallops; blue-black mussels; finely ridged skate-wing. Lately, no local display gets our minds to conjuring just the right compound butter or warm vinaigrette as quickly as Whole Foods' inviting berg of crushed ice. It's fresh, it's varied, and, surprisingly, it's not as expensive as those other chain grocers. So, lemon-chive butter on wild-caught coho or garlic-habañero mojo on tiger prawns?