First of all, DON'T REQUIRE ALL LOWERCASE. Cmon man, seriously? This is 2016. Don't force lowercase on usernames.
Secondly, I don't want to have to remember another password that I don't need to. By making me do this, I'll easily forget what I entered for a password when I signed up:
Third, where is the ability to change my password? Once logged in, I don't see a settings section.
All in all, I love the simplicity of your website. However, what do I do with the .txt file that I download? Is there anywhere I can re-upload it in order to change my list? How do I reorder my list? Do I have to do delete the rotator and then create a new one with a new order?
I will be playing around with your rotator script a bit more and give you some more feedback.