My favourites

Flower Bird's-eye speedwell or Germander speedwell (Veronica chamaedrys),
sunray/everlasting/strawflower (Rhodanthe chlorocephala)
Tree Scots pine (Pinus sylvestris), rowan or mountain ash (Sorbus aucuparia)
Mushroom (as food) Yellow chanterelle (Cantharellus cibarius), funnel chanterelle (Cantharellus tubaeformis)
Animal wolf (Canis lupus), stone marten or beech marten (Martes foina), Norway lemming (Lemmus lemmus)
Bird by appearance: coal tit (Parus ater), hooded crow (Corvus corone subsp. cornix), raven (Corvus corax), house sparrow (Passer domesticus)
by song: blackbird (Turdus merula)
Butterfly Blues (subfamily Polyommatinae), poplar admiral (Limenitis populi), purple emperor (Apatura iris)
Pet cat (Felis silvestris catus)
Stone flint (SiO2), granite
Mineral pyrite or iron pyrites (FeS2), quartz (SiO2)
Element silicon (Si), iron (Fe)
Metal silver (Ag)
Star Sirius
Constellation Orion
Moon crater Tycho (42°S 10°W)
Lunar mare Mare Crisium (Sea of Crises, 15°N 60°E)
Integer 2, 13, 15, 20, 37, 729
Irrational number pi (π ≈ 3,141592653589793), golden section or sectio aurea (Φ = (√5 + 1) / 2 ≈ 1,618033988749895 ; Φ-1 = Φ - 1 ; Φ2 = Φ + 1)
Integer sequence Fibonacci sequence (0,1,1,2,3,5,8,13,21,34,55,89,144,...), where every number is the sum of two previous ones (an+1 = an + an-1). The ratio of two consecutive terms closes to the value of the golden section. Any term can be calculated with the formula Fn = (Φn - (1 - Φ)n) / √5. This formula doesn't take into account the zero in the beginning, because it is disputed whether the zero belongs to the sequence.
Mathematical formula eiπ + 1 = 0
Language Finnish, Latin, English, Japanese, Classical Greek (specifically the classical Attic dialect), Old English, Sanskrit, Welsh, Lait
Script Devanagari (देवनागरी)
Vowel open back unrounded vowel [ɑ]
Name Krista [with Finnish pronunciation ['kris.tɑ], that is, with a rolled r and without vowel reduction], 舞 (Mai), 遥香 (Haruka)
Book His Dark Materials (Philip Pullman), The Lord of the Rings (J. R. R. Tolkien)
Poem The Raven (Edgar Allan Poe)
Comic Donald Duck, Ranma 1/2
Movie Bin-jip, Casino Royale, Chocolate, The Da Vinci Code, Dororo, Fearless, Forrest Gump, Inception, The Last Samurai, Memoirs of a Geisha, The Negotiator, 1941, Pirates of the Caribbean: At World's End, The Recruit, The Road Home, Spy Game, Twister
Series Azumanga Daioh, Babylon 5, MacGyver, The Mentalist, Navy NCIS: Naval Criminal Investigative Service, The O.C.
Actor Richard Dean Anderson, Jackie Chan, Kevin Costner, Tom Cruise, Harrison Ford, Mel Gibson, Tommy Lee Jones, Jet Li, Viggo Mortensen, Eddie Murphy, Leslie Nielsen, Brad Pitt, Gary Sinise, Will Smith, Denzel Washington, Bruce Willis
Actress Sandra Bullock, Judi Dench, Jodie Foster, Alyson Hannigan, Maki Horikita, Milla Jovovich, Ashley Judd, Jennifer Love Hewitt, Yuki Matsuoka (voice actress), Winona Ryder, Yanin Vismistananda, Zhang Ziyi
Music j-pop, film music, ragtime, classical, pop
Composer Scott Joplin, Richard Wagner, John Williams, Hans Zimmer
Artist/group AKB48, Berryz Koubou, Buono!, °C-ute, Momoiro Clover, Morning Musume, Onyanko Club
Instrument piano