I can't speak for various airlines, but I know that DL has a printed menu in BE on international flights, so you can be certain of what exactly will be offered (michelle bernstein and whatnot)

Domestically (in first) it can be a bit of a crapshoot. A breakfast flight will seemingly always have a choice of omelet or cereal. For lunch/dinner, they seem to have about 6-8 things that they rotate through, 2 of which will be offered on any given flight probably based on whatever catering decided to offer that day.