I was listening to Immortal - Tyrants with my good Sennheiser headphones on today instead of my usual creative speakers and I noticed how they subtley dubbed the vocals on the right side with like a whisper echo, and I thought that it was bad ass. I've heard stuff similar to that on other songs before, but it fits so well in that song. I thought it was a good song before, but its little details like that that make great songs. Also in When, by Opeth. I love the acoustic strums they play with the other guitars in the at the end of riff that starts at 1:27, before the first solo, also the riff the solo plays over. Post some other cool subtle things you hear in songs that make them great. I'm sure I know some more I just can't think of them right now. I'll post them when I think of them.