Some of my friends are for it, some are against it and I'm with my friends. :)
Personally, I generally don't. I don't want to be identified as a Christian by my co-workers by my "pious acts" but rather by my Christian acts that they would not view as a public "show" of my religion.
Lately Tim Tebow has taken the issue of public displays of personal piety to a new level. (Not that no athlete has ever crossed themselves, prayed or knelt in the end zone before). But for some reason he has spawned an "in your face" public piety that I think speaks of the polarization of evangelical American Christianity and the culture more than perhaps the piety and beliefs of those who practice it.
I will lay aside the fact that "this is a free country and we can pray, bow, chant or stand on our heads for Christ, Allah, Zeus, the Cosmic Chicken King, or our Fairy God-mother." That is not the issue. What we are free to do does not make doing it edifying nor compelling to those who watch.
The issue for me is, who is it for and what does it accomplish?
Of course there are those who think crossing, praying in public and Tebowing are "standing up for Christ". Perhaps. It does take a degree of either courage or social unawareness to do something in public that would be viewed as stupid or offensive by some. However, doing something socially awkward and offensive, even if it is well intended or even religiously motivated doesn't make it good, it just means the "doer" is well, offensive and awkward. That's why multi-level marketing works. And just because someone is insulted for a display of anything doesn't make one a martyr for the cause. Street evangelists with loudspeakers who harass passers-by are rightfully persecuted for being annoying asses whether they are selling cell phone plans or salvation. But is this all on the same level as crossing one's self before a meal in front of friends?
The questions for me are: "Is it really standing up for Christ?" and "Who is it for?" Personally, I tend to think of religious displays done publicly as standing on the street corner making a show that might impress some other Christians. I think it drives a wedge between me and a cynical unbeliever that I would never reach with pious behavior but possibly can reach with love. I would rather have someone not be surprised if they saw me cross myself than to be surprised that I DO cross myself, if you get my drift. The "aroma of Christ" and the "adornment of holiness" is, according to St. Paul, our lives, not our words or "washing of hands" in public. The true sign of the Cross is the crucified life, the outward sign (the "icon", if you will) of the Cross must have a correspondence to something real (incarnate, if you will) to those who witness it. Without the correspondence and integrity of the incarnate and the sign/icon, the outward is merely a potential for an awkward moment or possibly an offense, and perhaps worse, an hypocrisy waiting to be called out. That is why I don't buy making the sign of the cross as a particularly good thing to do even though it is congruent with the fine points of Orthodox theology. We should not expect to be judged favorably or accurately by those who do not share our theological paradigm, nor should we begin "teaching them" about our faith with displays of private piety and the esoterica of our religion. Our initial point of contact should be the common ground of both our experiences and expectations of "true religion" (and ultimately what the sign of the Cross really MEANS and really points both of us to): self sacrificial love for one's neighbor. Even the irreligious can understand that and can be impressed by it. Becoming all things to all men, according to St. Paul, sometimes means giving up the trappings of our personal piety in order to not be judged wrongly by the unbeliever.
IF someone I know ever converts and asks why I didn't cross myself and pray in front of them, I'd just say I didn't want to make them uncomfortable or offend them out of respect for their beliefs at the time.
All that said, I'm inconsistent and it depends on who I am with. I generally pray or cross myself if I am with other Christians (even some evangelicals). I generally don't in a mixed group with people I don't know and who don't know me well enough to know I am either a Christian or at least a "helluva nice guy". If I'm eating alone or when I DO make a sign of the Cross in a public setting, I keep it small and quick because its for me, not everyone else.
So for me, I'd rather be seen in public taking up my cross and dying to myself than crossing myself. Of course, it's not an "either/or" but I better be damned sure if I go for the "both/and" I better have both lest I put the Cross to open shame and hold it up to public ridicule by my actions (I think St. Paul in Hebrews has something about that...).
By the way, yes, I'd put an icon in my cubicle.