The following keywords are related to information from very specific fields, many of which may be considered hobbies by some people. But one man's hobby is another's arcane knowledge, so they are grouped together here.
abacus
Advice Animal meme
alchemy symbols
American Girl dolls
angelic hierarchy
apocalypse dates
Ars Goetia
ashtamangala
astrology
Aztec calendar
Babylonian numerals
baby names database
ballroom dancing
Barbie dolls
Beanie Babies
bee waggle dance
Bhavacakra (Buddhist Wheel of Life)
bird calls
blueprints
calculatrivia
cannabis: see marijuana
castrated animals
celebrities' original names
celebrity deaths
ceramics
change ringing
Chinese zodiac/calendar
circular periodic table
coats of arms
collective names for animals
combination locks
"Cooking with Dog" (YouTube show)
costumes
Crayola colors
crocheting
cross-stitch
crosswordese
cures
currency ISO codes
dancing
demons
dog food
dog hybrids
dog shows
drill sizes
DTMF dialing tones: see Touch Tone dialing tones (DTMF)
Ermahgerd! meme
etsy.com
expired facts
eye chart
fashion designers
fictional dogs
fictional weapons
flower meanings
four horsemen of the apocalypse
full moon names: see moon names from Farmers' Almanac
Garbage Pail Kids
Gen Con
geomancy
ghost leg
ghosts
G.I. Joe
guns
haunted places
Hebrew numerals
heraldry
hexagon dancing
high school CEEB codes
hillside letters
hobbies
Icelandic Yule Lads
invisible ink
Iraqi Most Wanted playing cards
juggling
knitting
knitting patterns
Konami code
The Language of Flowers: An Alphabet of Floral Emblems
Lao numerals
Latke vs. Hamentaschen debates
Lego
lip reading
magic tricks
marching band drill sheets
marijuana
Marvel alternate Earths
Maslow's Hierarchy of Needs
medical names for conditions
military pay grades
military ranks
MIT named rooms
moon names from Farmers' Almanac
musical instruments
mustaches
My Little Pony
mythical beasts
nail polish colors
Name of the Year
navigation way points (fixes)
nerdy pastimes
nicknames
nicknames for playing cards
non-water floods
novelty architecture
numerology
paper airplanes
paper dolls
parts with unusual names
phone phreaking
picking locks
Piet programming language
Popy Chogokin robot toys
pot: see marijuana
punch cards
Queen Elizabeth's corgis
quilting
quipu
Rainbow Serpent
rescue and salvage ships
ribbons (substitute military medals)
rigged dice
ring sizes
roadside attractions
Roscolux lighting filters
Rube Goldberg machines
scouting
selfies
sephiroth (tree of life)
soil types
Sporcle (trivia web site)
square dancing
stages of grief
state superme court seals
Strava (cycling and running app)
swing dancing
the Taco Bell $2 bill story
Tamil numerals
tarot cards
Thai numerals
The Happy Squirrel (tarot card introduced by The Simpsons)
Touch Tone dialing tones (DTMF)
Transformers
tree of life (cabbala)
turkeys pardoned by the U.S. President
Vikings
voting systems
Voyager Golden Record
Wacky Packages trading cards
Webby awards speeches
weird laws
West Coast Swing Dancing
Westminster Kennel Club
Whitman coin folders
yoga poses (asanas)
zodiac