Friendster
Mindsay
Literature
Constructed languages (conlanging)
Geofiction, including model nations
Learning foreign languages
Reading and bibliophilia
Penpal
Writing
Zines
Model (scale model) building
Live steam models
Matchstick models
Military models
Model aircraft
Model cars, including radio-controlled cars
Model commercial vehicles
Model engineering (Machining)
Model houses
Model figures
Model military vehicles
Model nations
Model railways/railroads
Backyard railroads
Model rockets
Model yachting
Music
Karaoke
Musical composition and MIDI composition
Singing and playing musical instruments
Songwriting
Listening to music
Observation
Amateur astronomy
Bird watching
Geyser gazing
Horoscopes
People/crowd watching
Transportation spotting (see below)
Outdoor/nature activities
Airsoft
Backpacking
Birdfeeding, birding, and birdwatching
Bouldering
Buildering or urban climbing
Butterfly watching
Camping
Caving
Canoeing and kayaking
Fishing
Gardening (forest gardening, organic gardening, wildlife gardening, bonsai, and permaculture)
Geocaching
Ghost Hunting
Hacky Sack/footbag
Hiking
Historical Trekking
Horse riding
Hunting
Kite flying
Laser skirmish
Letterboxing
Mountain climbing
Nudism
Paintball
Rafting
Rock climbing
Rockhounding (rock and mineral hunting/collecting)
Ice Skating
Plinking
Sailing
SCUBA diving
Sight seeing
Skiing
Skateboarding
Snorkeling (Snorkelling)
Snowboarding
Survival Camping
Stone skipping
Traveling
Treasure hunting (possibly with metal detectors)
Urban Exploration
Walking
Performing arts
Amateur theater
Dancing
Juggling
Magic tricks
Singing
Poetry reading
Bhangra Dancing