I have been but never reported it, I didn't want to be known to my co-workers as the girl who was sexually harassed or worse the girl who allowed herself to be (the latter is sad to say but it's true). I figured, I'm an adult, I can handle this without becoming the main subject to rampant workplace gossip. Although, I did speak to some friends about it and received a few colorful solutions, most of them violent in nature. Just so you know, I didn't act on any of them.
In my opinion, the first thing to do in a situation like this is to approach your offender, he or she might not even be aware of their actions. However, if the offending behavior continues, it's best to involve upper management. In addition, having a witness or solid proof of the harassment will help significantly. Otherwise, it's just your word against your offender's, which poses its own challenges if they outrank you.
What constitutes sexual harassment.
(Pictures via here)