The dependency on Facebook is kind of unfortunate, as it excludes those who either don't have a Facebook account, or for various reasons do not want to use it to sign up for services. I am myself in the latter category, but went with it as I wanted a single login, and saw it as the best alternative at the time - got some more about that in the 'why Facebook?' section on the site.

Would really like to provide a solution that could work without login, but I'm kinda clueless on how to solve this in a good way, that allows for the creator not knowing what has been checked off or not, as well as allowing others to both check and later - perhaps even on another device - uncheck items :/