I see people every day who are just waiting, for some sort of physical and visible mark forced upon them. And this is not what God told us to beware of. He said to choose the right mark, a mark you receive freely and on purpose. He defines them clearly. The mark on the forehead is in your thoughts, the mark on your hand is the work done.
Either is a mark of slavery. Now, because you are free, you can choose to keep God in your mind and perform work that actually produces results; or you can choose to keep the mark you were born under, of the flesh and the beast and ultimately, that mark and number look a lot like this:
$6.66.