You have to figure that for astronauts, being in space is awesome enough that they won't be particularly picky about food. And you'd probably be right. But there's more to space food than taste: whatever spacemen and spacewomen eat has to be nutritionally complete, not get anyone sick and be stable enough to survive for months.
NASA's got a whole laboratory dedicated to the study and improvement of space food, called the Space Food Systems Laboratory (SFSL), and most recently, the lab has been working on ways to implement a bioregenerative food system for Mars habitats. New menus include such tasty items as African Sweet Potato and Peanut Soup, Flourless Peanut Butter Cookies and Spanish Rice.
Menus weren't always so exotic, though. In this gallery, we've got space food ranging from Mercury and Gemini all the way up through the Shuttle era and the ISS. We couldn't spot any marshmallow fluff, but we have it on good authority that there's some squirreled away up there anyway.