Worker bees crowding around entrance to hive...

Recently (within the last two weeks or so) our honeybees have been gathering in large numbers (abt. one hundred or so) around mainly the bottom entrance to our beehive. They aren't really crawling on one another - they are mainly gathering on the same level, sometimes in lines. This happens to some extent during the day (the picture is of this), but they start really grouping up around nightfall.

I have also spotted a drone several feet outside the hive. He seemed very weak.

Does anyone know what this means?

Thank you!

Looks like they are 'washboarding' or line dancing.
Some scientists say that they don't know why they do that. Our local bee guru told me that as the nectar flow slows way down, these are the forager bees that have a lot of foraging energy but no source to forage from. What they do is plant their back feet and move forward and backward using only their front feet. They lick or polish the side of the super. I was told that if you see your bees washboarding that you have very productive genetics in your bees! Good!
Google honeybee washboarding and see if that's what your girls are doing.

Another reason bees cluster at the entrance is due to the hive overheating, they'll fan their wings at the entrance to create a draft to cool things down.

This is the time of year that the girls will start to boot the drones out. That's normal.

Here are some videos of my girls washboarding
http://www.flickr.com/search/?w=95096591@N00&q=washboarding

Thanks! I think it is washboarding, since I haven't seen them fanning their wings.