Dropbox - don’t give full access to your machine

Dropbox is a widely used program but they have a wide-open back door which allows them to circumvent Apple’s (good) security features. Upon startup, they ask for you to enter your administrator password into their dialog box. After that, they can do anything with your machine. If you just cancel the dialog and start Dropbox up manually, they have all your files, but at least they don’t own your machine.