Metallica - Metallica (First pressing, 1991)
Metalheads are willing to shell out a lot of cash for original copies of this LP. Suddenly that Napster fiasco makes a lot more sense.
Tom Petty - Wildflowers (First pressing, 1994)
Found this later Tom Petty release in your Dad's collection? Sell it now. If they ever get around to rereleasing it on vinyl you can expect the value to plummet more quickly than Petty's post-'90s talent.
The Alan Parsons Project - I Robot (Limited edition, 1983)
If you find this album in the basement, I'd be willing to bet your parents have another, even more valuable stash hidden somewhere nearby.
Bruce Springsteen - The Rising (First pressing, 2002)
It's a Springsteen album that's not old enough for a reissue yet, which means two things: vinyl copies are valuable, and fans still try to convince themselves they loved it.