Agree with the others that "hard rock" is a vague category, but I'll give it a go anyway.
First if you haven't already, check out Velvet Revolver. They have one album ("Contraband") and it's not the greatest record you ever heard, but it's a pretty decent straight-ahead rock and roll album.
Second, check out L.A. Guns' first record ("L.A. Guns"). It's very raw and not like their later, more "hair band-ish" records. Like AC/DC, all the songs on the record sound the same, but it works because it happens to be one great ******' song.
As for something truly "lesser known," check out the first album by Zodiac Mindwarp and the Love Reaction ("Tattooed Beat Messiah"). These guys were moderately successful in the UK for about 2 weeks in the 80s before dropping off the face of the earth, but this record really rocks.
Finally, and this is really hard to admit, but I absolutely
love the debut albums of both Faster Pussycat and the Bulletboys. In both cases, you have to get past the hair spray and the lipstick, but if you can do that they're both great, extremely simple, three-chord rock and roll parties.
I'll let you know if you think of any more. Do tell what you're currently listening to that you're getting sick of. If you like AC/DC, Guns N Roses or any 1980s pop "metal" (using that word very loosely), I think you would like all of the above.
