I'll never forget sitting at my computer listening to digital cable radio and heard this band with the brutal / clean dynamic. I turned around and had to squint to see the name...Opeth. Went to fucking Best Buy and bought BWP and never turned back. Now I have all the albums, the DVD, and have become a fan of Bloodbath, Katatonia, and Porcupine Tree.
I also have made my way into the list of "similar bands" on allmusic.com's Opeth guide. Of course, many of these are discussed here as well: Ulver, Dark Tranquility, Edge of Sanity, etc. (Strange, though, that damn Tiamat reference one of the reviewers mentions...Tiamat sucks.)