I recently moved to a new place and I am so excited because I have a spare room. My mother likes to call it the guest room. I call it the yarn room!
But we lived in a fairly small place before and bought a folding table to be used as a craft/activity desk. I put a nice long table cloth on it, and then undernearth I stored all my yarn in plastic bins. The bins mentioned in this thread from target would be perfect under a table.
But I also have a small bag that I keep whatever is my current project in for mobility sake.