I am one of those people that obsesses (learns everything about a subject) and then moves on, so my list would be way too long for anyone to want to read, but some of the stranger things include:
[ul]
[li]rocks, minerals, crystals – this was in 4th grade, and I can still recognise far too many with ease[/li][li]playing violin, I wish I could focus enough to become better, but it took me about a month to get the basics and learn one song[/li][li]Marie Antoinette[/li][li]The Bell Witch – who, contrary to what the name implies appears to be more of a poltergeist than anything else, going by textbook definitions[/li][li]cat genetics[/li][/ul]
Yes, I know far too much about far too many subjects. It’s a sickness.
Wood (as in, 200+ samples of different wood species in my basement stash, every unmarked piece identifiable by me, with a Latin name, in a couple seconds).
Guillotines (ever since as a child, I’ve had a fascination for these über-cool machines, spending class by drawing up guillotine blade release mechanisms etc.)
World records. (Not having read the Guinness book or other source for two decades, I can still cite many obscure records by name and year, by heart).
Mine has been:
UFOs
Vampires
Neo-Paganism [even though I’ve been Pagan since 1989]
Pre-existence & Reincarnation
Rocks, minerals and crystals
Horse genetics
How nuclear reactors work
RMS Titanic - I went through a phase when I was 7 or 8 years old that I was absolutely obssessed with the ship and its 1912 loss. My mom tells a story about me once running home so excitedly from school and bursting through the door, she thought I must have gotten an A+ on an exam or gotten my first kiss. I shouted, “Did you know that the bars on British ships open at 2pm on Sundays?” (or some other similarly obscure factoid; I don’t remember the incident but don’t doubt her in the least).
World War II, especially warplanes - In my early teens.
Star Trek and Star Wars- In my later teens, and still a bit today.
The American Civil War - From the time of the Ken Burns PBS series, more or less through to today.
LOTR and Tolkien’s other writings - For a couple of decades now. When my older sister, whose interest in Tolkien long predated mine, said (unprompted by me) that my knowledge of Middle-earth had surpassed hers, I was one happy camper.
American historic flags - Since my Boy Scout days.
Alice Cooper
Quiet Riot
Gaelig (although I’ve forgotten almost all of it)
Walter Macken
Anne Rice (and her books)
Palmistry
Astrology
Tarot
Ghost Hunting
cemetaries
Runes - there was a time when I could write letters using Runes as the alphabet and could read them fluently as well.
My biggest obsessive-must-learn-everything-about topics of the last decade:
-WWII history
-Fountain pens
-Square-rigged tall ships & the history of the British navy in the Napoleonic wars
-the 1911 pistol & handgun markmanship
-WWI history