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The only piece of personal information required is your email address, so that I can notify you of changes and especially improvements to the site or your account. Plus it's needed to help you reset your password in case you forget it.
I won't sell your email address to anyone, because none of us needs any more junk mail than we already receive.
In the event some big company wants to acquire the site, then of course they'll get the site along with its database. But then all they'll have is your email address, which you can change if you really want to.