I lookd through the hive yesterday, and there's LOADS of honey--I didn't look through EVERY frame, but I saw no brood. There were also several things that looked like queen cells, but they were brown and rather small and empty.

Today there are bees all over the front of the hive. Just covering the front of the bottom box. Does that sound like something they would do if they maybe were ready to swarm but didn't have a queen?