The list could go on for miles, but I'll add the Norwegian albums worth investigating for heavy content and come back to other countries later.
Aunt Mary - Loaded 1972 (great Purple/Heep-like hard rock with prominent Hammond.)
Aunt Mary - Janus 1973 (much more progressive, but still quite heavy)
Høst - På sterke vinger 1974(brilliant hard rock, some riffs are almost Maiden-like)
Høst - Hardt mot hardt 1976 (much more progressive and less heavy. Only for thos who like it progressive)
There's also a "Live and unreleased" by Høst which is well worth getting.
Ruphus - New born day 1973 (loads of organ and great female vocals)
Freddy Lindquist - Menu 1970 (only occasionally heavy, but with some great guitar work. Some more stuff that's more pop, but a good album)
Junipher Greene - Friendship 1971 (this one really isn't all that heavy for the most part, but it's a brilliant piece of progressive rock with more guitar than most of it's ilk)
Flax (had a couple of albums too, but I never was impressed by them. I know some people love their stuff though.
Subway Suck made an album as well. It has quite a bit of punk in it, but it's a pretty good "proto-metal" album if you count things like Christ Child in that bracket. Goes for about €100.
I know I ain't doing much,
doing nothing means a lot to me.