I just learned how to use WP and have set up three different blogs, one of which was a theme designed by myself. I say this not to gloat about my accomplishment, but to give credit to the authors and others who have developed WP to be a fine application, easy to learn, well documented, and able to suit many needs.
That being said, I wish that WP had within its basic features an option where an administrator of a blog could screen and approve people who want to register. Right now the only options are to let everyone or no one to register.
I spent many hours trying to find a plugin which would give me that administrative register option, but alas, many did not work; and I am left trying to figure out a way to allow people to register but screen them. Personally, I do not have the coding skills to write scripts to do this.
For such a basic feature as the above, I would gladly pay at this point.