"Here is the mind which has WISDOM.
Wisdom and understanding in end time visions require awareness or the ability to calculate (Daniel 12:5-10-13 and Revelation 13:18). This sentence is placed here to say, in effect, "Don't predetermine what the content of this triplet of verses (verses 9-11) may mean." (Romans 11:33-36)
Ever since the seven angels came from the temple with the seven bowl judgments (Revelation 15:8 and Revelation 17:1), the context of this scripture is spiritual. To try to place this triplet into geopolitical terms (mostly Rome) is not demonstrating WISDOM in my viewpoint. Rather, we must continue to be alert to current events to recognize when these things will come to pass (perhaps within our lifetimes???). This is equivalent to having oil in the lamps in anticipation for the wedding (Matthew 25:1-13).
The seven HEADS are seven MOUNTAINS on which the woman sits,
MOUNTAINS in prophetical writings have referred to world powers (Isaiah 2:2-4; Jeremiah 51:24-26; Daniel 2:31-35; Zechariah 4:1-7). In this context, these are worldwide spiritual powers.
Consistently throughout Revelation, the number seven indicates completeness. Then this portion means that the seven HEADS are the complete organizational embodiment of the evil power of the beast. Also, the woman, the socioreligious organization in power at this time, is freely transported worldwide by the beast. That is, there will be no travel restrictions on those who have taken the mark of the beast. Note, though, that the beast puts up with this arrangement as long as the woman is useful to him (verse 16).
With the hindsight of September 11th, a person could argue this represents seven major terrorist cells operating worldwide. What little we do know of al Quaida, it has strong religious overtones and is well funded with "oil money" (Revelation 18:15).