Now to address the question at hand, "IS THE MARK OF THE BEAST A MICROCHIP, A BAR CODE, OR SOMETHING ELSE?" I have seen a lot people ask about this subject. There are some that have used "The Mark of the Beast" as a scare tactic! Then there are others that genuine in their thoughts, teachings, and warnings about this subject but I do see this group as the minority on the subject.
Here are the Bible Scriptures that refer to this subject: Revelation 13:16-17, 14:9-10, 19:20, 20:4, if you would like to reference them.
Let me start by saying, "NO ONE (and I repeat NO ONE!) can accidentally take "The Mark of the Beast"! To not take "the mark" is a willful and calculated choice to serve and follow the Lord. Just like, to take it is a willful and calculated decision to serve and follow satan. Yes, this technology, whether it be this one or a multitude of others, will allow for easy identification of this following the beast but to have a "chip" under your skin for work, gym, purchases, or other purposes cannot fall in line with scripture. Just like you can't accidentally be a Christian, you also cannot accidentally take "The Mark of the Beast"! That does not mean that you cannot be deceived to taking it because Scripture is clear that even the elect can and will be in the last days. But again there is choice involved in this! Understand, the first and foremost thing we must do as Believers is follow close to the Lord and as we do all these other things will fall into place. Stay on our guard and be vigilant to the "wiles ans schemes of the evil one"!
Also, I found this article and hope it helps on the subject as well.
Here are two different places for further study on this subject:
Bro. W. Dee Daniel