…marry me! I love this thread and I love your choices! 
Right off the bat, I have to list “Sir Psycho Sexy” by the Red Hot Chili Peppers. (although they are hard to categorize as anything, I’ll take the plunge and call them “hard rock.”) Actually, any RHCP song pre-“One Hot Minute” is good, but again, might not be considered hard rock.
I have to agree with astorian about “No More Tears.” For the longest time I wanted to get Ozzy’s name tattooed across my fingers, like he does. Pretty much anything by Black Sabbath kicks the ass of anything out there today, but “Iron Man” and “War Pigs” stick out in my mind.
“Sweet Child O’ Mine” by Guns N’ Roses, if for nothing else than the opening guitar riff.
“One,” “Master of Puppets,” “Seek and Destroy,” and “Enter Sandman” by Metallica, and pretty much anything off “the black album” or before.
Living Dead Girl hit the nail on the head with her “anything by Tool” comment. (Oh man, I didn’t realize that I just made a horrible pun - “nail on the head” - Tool … Jeez…), but particularly “Sober” and “Prison Sex.”
And finally, “Snap Your Fingers, Snap Your Neck” by Prong and “Walk” by Pantera are usually played on the radio one right after the other (it’s a rock-n-wrestling radio program and there are two wrestlers who use those as entrance music [for those who care or are curious, Justin Credible and Rob Van Dam, respectively]) and it could possibly be my favorite ten minutes of radio during the day
I know I’ll be back, cuz I know I’ll think of more, but I’m drawing a blank right now.
-Syko
“My cat’s breath smells like cat food.” - Ralph Wiggum