It is true for the most part that invites/acceptances, etc. are pretty much out of our hands once we have completed files. However, I have heard several accounts of applicants who, having received no invites as late as Feb., started calling the admissions dept. and before long they were interviewed and subsequently accepted. I know the majority of people on here would say that calling, sending LOIs, etc. does little to sway the adcoms' decisions, but I refuse to believe there is no transference of info between the admissions dept. and the committee. This isn't to say that one should pester the school's admissions director, but I think you can both let the school know how serious you are and glean some info regarding where you stand in terms of interviews/accptances by calling.
Side note:

another wednesday with no phone calls!! Here's what I'm wondering: since USF will probably stop interviewing some time after Dec. 17 until around the 14th of Jan, invites for Jan. would have to be done before Christmas break right? so maybe there's still hope of hearing something before then. I'm just so disappointed right now. Another stupid waitlist with FSU and now silence from practically everywhere else. From the looks of it SoFlaKnight hasn't gotten any love from USF either. Waiting sucks; especially when your family buys you Harrison's principles of IM as a birthday gift. Thanks mom and dad; wish I had an acceptance to go along with it.