Not all of these still blow my mind currently, but there have been a few:

The Dark Side of the Moon - Pink Floyd
When I first listened to this album in high school, it did literally blow my mind. I listened to it at every possible moment for about two months straight after buying it. I still love Dark Side obviously, but I wouldn't say it still has quite the same impact, though I still get chills from "The Great Gig in the Sky" and the way "Brain Damage" melts into "Eclipse."

Tonight the Stars Revolt! - Powerman 5000
This was another huge high school album, but where Floyd more spoke to the artsy-nerd side of me, Powerman fed the angry teenager side. This was a GREAT album to listen to on headphones whilst stalking through the mall, being mallratty, daring people to mess with you. I remember my group of friends not really knowing anything about Powerman when they first came out other than "isn't Rob Zombie's brother in that band?" and not really caring. Then one kid in my group bought it the day it came out and let us listen to it and I immediately started walking from downtown to the mall to go get my own copy. Which wasn't all that far, but I was a fat kid in a leather jacket, camo pants and army boots and this was midsummer I think. Now, it's still a fun album, the songs are just as catchy, I just don't listen to that kind genre so much anymore.

Yoshimi Battles the pink Robots - The Flaming Lips
This is the album that got me into The Lips and Jesus Christ, I can't believe it came out thirteen fucking years ago. Anyway, this was another one that really took hold on my mind with the combo of relatable (if in broad, metaphoric strokes) themes with trippy space noise basically. Much like Dark Side, I listened to this for months straight after it came out. Now, I still consider it a real winner. I don't know if it's my favorite Lips album, but it's definitely the first one I would tell people who have never heard of them to listen to first. It has none of the aural weirdness some of their earlier albums, except Yoshimi Battles the Pink Robots Part 2, and it all meshes together well from track to track without jarring you out of it.

Blood Money - Tom Waits
Hearing this one was what got me into Tom Waits. My roommate in college during my freshman year was really into Tom Waits and he played this album for me and it did indeed blow my mind. If my memoration is correct, my description of "Misery is the River of the World" to him was that it sounded like an ogre playing a xylophone made of human bones while singing. This being Tom Waits, he then goes a whole bunch of other places with his voice that are completely different and I imagine that's how he attracts new fans, worked with me.