Right on, Club 33 This is the very first thing that came to my mind. There is a certain stretch of Hawthorne Blvd. on the way to Palos Verdes that smells like that (not sure if there’s a resevoir nearby, or some kind of drainage thing or what). The odd look I received after proclaiming “oooh, it smells like the Pirates of the Carribean!” was enough to tell me this is not a well known phenomenom.
Maybe not all that odd. My brother the Disney freak tells me that on Disney message boards, a common thread is “what smells remind you of Disneyland?”, and a common response is stagnant water = PotC.
Gasoline - Don’t know why, but when I’m filling up my car I always take a deep whiff.
Vanilla - When my wife is baking and is going to use some vanilla, she always calls me over for a deeeeeep inhale. She knows I need my fix.
Chocolate - Next time you open a bag of Hershey’s Kisses, take a good sniff. Frabjous.
Old books - I love that pulpy, slightly musty smell. Hardcovers from before the 1950s, and paperbacks from the 1950s and 1960s, are best.
Mothballs - This is mostly for sentimental reasons. Always reminds me of getting out woolens for the winter, and looking forward to sledding, snowball fights, etc.
There’s actually a word for it: petrichor. One of my favorite smells of all time, after sycamore trees.
K other’s have mentioned these, but I’m puttin’ them here all in one place:
Gun Oil - I haven’t been around firearms in 20 years, but that smell takes me right back
Brakleen, WD-40, Kerosene, MEK, Tolulene, Gas - pretty near any petroleum product, which takes me to:
Test’n’tune night at the Drag races. The smell is an amalgam of hot rubber, high octane race fuel, hot motor, anti-freeze, and adrenalyn. MAN it’s time for racin’ season again!
hot good strong coffee.
Simple Solution Cat pee enzyme cleaner stuff. I dunno why, but other brands made me retch. I lost both cats within 4 weeks last year. I don’t miss the pee or the barf, but I do miss the cats.
myself…my second ex wife (love o’ me life) and lots of other like-minded-humanfolk…
it’s my own little *jitterbug pefume’
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peace, love and any smell that makes ypu simile… 
I love the smell of musty basements. And Youth Dew perfume.