A band I joined years ago had a couple of quite heavily-metaly tracks and quite by accident I found that these parts worked extremely well at the organ. I was actually practicing for a choral concert, remembered that it was my first band rehearsal that night and thought I'd better have a look at the charts they'd given me. Ironically, I'd been listening to the practice tape they'd made, thinking "what on earth can I add to this?" then, when I started playing at the organ I thought "okay, this really works!" Of course, I could rely on old faithful to save me! Thankfully, I had some decent organ samples on one of my synths and didn't have to take the pipes with me (fun though that would have been).
Muse have done some heavy-ish tracks with pipe organ on them.
Not sure what the interest is - maybe it's the instrument's association with things Gothic.