[chad_oliver]

I saw "Post to my wall", and closed the tab. Why is this necessary? And why do you want my email address?

[ndroo]

Email address is used to send you a daily report of changes (if there are changes) they're not stored or used for any other means.

Post to your wall is how the app spreads, but you can disable that if you do not like it :-) There is an option in settings once in the app.