I've been hawk-eyeing this conversation, and you bring up a good point. I'm brand new to RP'ing, and luck is the only thing that has saved me from asking yes/no questions or answering with a yes/no answer. So now what I'm going to try to do is, when my characters ask a question, I'll leave avenues open. Like "we could do this, or maybe this, or perhaps this." It gives the person responding a little more to work with.
That said, if you have to respond to a yes/no question, it would be a good time to add some description. Like a character checking his watch to see what time it is, or describing something important going on, or the like. Or even adding details to help with character building, like having a shy person hesitate or blush to maintain the character's persona in everyone's mind. This wouldn't always be a viable option, obviously, but it definitely would help with the "'yes,' so-and-so character answered." posts.