It depends on what you think you'll get out of it. If you're just looking to express some ideas, thoughts, and emotions on your journey well the journals are below and a notebook is cheap. If you're looking to interact with people the journals are below. If you're looking to build your own community you may need a new approach to FI as that market is fairly saturated IMO.
As for the anonymity aspect, well that depends on how open you are today as a person. Would you go up to your friends and tell them verbally your net worth? If no then you probably should take care to not do that electronically. Would you put a sign up outside of your house showing your expenses and income? If no then you should probably not post it. Starting a blog is exposing a portion of yourself to the world. People can find out who you are, keep that in mind.
:)