Ability to select a folder
Currently, there is no way to select a folder for looping over a directory. I know, you could work around that by choosing any file in that directory and use its path, but selecting a directory directly would be less confusing to the user.
I think it could be a nice addition to the assets fieldtype, to allow selecting directories (additionally or only). This would result (depending on whether you can additionally select or only select a folder) in a new button like this:

What do you think?
I like it! I'm not sure exactly how it would/could work with the existing assets fieldtype, but it's a good idea.
I'm currently looking for this type of functionality as well.
I want to create an asset download block for branding and images. It would be great if I can just select the entire folder with all the assets that should displayed in this block. Then, if images are added or removed from this directory it will automatically be propagated to this block without having to reselect assets in the CMS.