Word of mouth is the primary driver when it comes to discovering new metal bands. It's always been this way. When I was younger, we used to give cassettes to each other. Now we pass along links. Here's one: Fughu, a talented progressive metal band from Argentina. These guys recently opened for Dream Theater in their home country, and released a self-produced album titled Absence last year.
I like their sound (especially the vocalist - this guy's got pipes), but the production is a little undercooked. Get these guys in a studio with a top-tier producer / mixer who can tighten up their songwriting and refine their sound and I predict big things for this band.