This can be a rather controversial subject. Even among those who believe the gift of prophecy is still in operation today, few can agree upon who is actually a genuine prophet of Yah.
Still, I believe there are some genuine modern day prophets Yah has appointed as watchmen in these last days. I certainly don't claim to know all of them, but here are a few that you may want to read up on yourself.
Dumitru Duduman was a Romanian who underwent severe persecution under Communism. His story of faith under grueling circumstances is an inspiring testimony to any believer. YahShua opened the doors for Dumitru to escape Communism and relocate in the United States in the early 1980's.
For the next 16 years, Dumitru received dream after dream, vision after vision depicting the judgment about to fall upon the USA. Dumitru is a verified true prophet because he predicted Romania would have a revolution before the USA would be judged. Romania, of course, had had her violent revolution rather recently.
You can read his collection of dreams and visions on his website <http://www.handofhelp.com/>. His hard-hitting message against sin and his prophetic judgments of doom against the USA were largely rejected by modern Churchianity. Dumitru died in 1996, sleeping in YahShua until the day when he shall receive his reward. He was certainly a modern-day prophet.
David Wilkerson is another one. He has published several books about the coming financial collapse of the USA. He has also prophesied similar judgments coinciding with Duduman's revelations. I highly recommend reading his book, "America's Last Call" which you can order from Amazon.com <http://www.amazon.com/>. His messages are also fortified by strong warnings to both the church and the nation to repent and turn back to Yah.
Henry Gruver has a ministry of walking up and down the streets of various cities, praying against devilish strongholds and doing mighty spiritual warfare. In the course of his prayer walking ministry, Yah began to give Henry startling visions of Russian subs launching a full scale nuclear attack on America. If you visit the Prophecy Club <http://www.prophecyclub.com/> website you can order Gruver's videos which I highly recommend. You will discover his spirit of humility and righteousness refreshing as he pleads with this nation to repent.
Michael John Rood is a Messianic teacher who has used the Feasts of YHVH as a template for understanding the book of Daniel and Revelation. He simply uses Scripture to clearly outline what is about to come to pass. His eight-tape series, "From Here to Eternity" carefully details the agenda of the New World Order and goes page by page through the book of Revelation from a distinctly Jewish perspective. Another eight-tape series, "The Mystery of Inquity", is an excellent companion and peels back the layers of paganism and deception that has invaded Christianity. His message, of course, is undergirded by a strong message to return to the Ancient Paths, begin keeping Torah, and shedding the paganism in modern Christianity.
The above list of modern-day prophets is in no way intended to be exhaustive, but a mere starting point to hear what the Ruach Ha'Kadosh is speaking to His prophets today. I think upon examining their materials and listening to their message you will be compelled to agree that these men truly speak from YahShua's Spirit.