Pinch harmonics aka "squealies"
I love them so much. Some people hate them, but for me they're one of the coolest aspects of guitar playing in metal.
Recommend me some albums/songs that use them a lot. (No need to mention Dimebag Darrel or Zakk Wylde, those are pretty obvious)
I've been listening to these two recently:

The obvious answer is Children Of Bodom.

I've been listening to a lot of Primal Fear over the past few days, and they seem to like throwing in pinch harmonics. Eg



Sentenced - May Today Become the Day I think might fit the bill too.

I love pinch harmonics. Althought Malignancy isnt my favorite band they certainly make heavy use of pinch harmonics. https://www.youtube.com/watch?v=VG3z-v7DfOM