I really love yellow and navy together—it's so cheery but accommodates a bad day which is very important. It's a common enough color combination that you can find a cushion or other accent homeware item in order to bring the idea into the room without having to commit to a yellow or navy wall. In fact, it's probably better to keep it little more subtle - a little goes a long way with this combination I think. Here are some interiors that got it right.
images from top left and across: blue lamp // yellow stools // yellow ottoman // yellow table // yellow door // blue patterned couch // blue door // "rock" // hydrangeas // blue wall // patterned yellow chairs // yellow couch