Name 20 animes that aren't mainstream.

Well, it depends on what 당신 consider mainstream, really.
But, whatever.

1. Amnesia
2. Kamigami no Asobi
3. Meganebu!
4. Tsuritama
5. Bokusatsu Tenshi Dokuro-Chan
6. Shinryaku!? Ika Musume!
7. gdgd Fairies
8. Hoozuki no Reitetsu
9. Petshop of Horrors
10. Princess Jellyfish
11. Kimi to Boku
12. Kiniro Mosaic
13. Mitsudomoe
14. Nanaka 6/17
15. Nyan Koi
16. Daily Lives of High School Boys
17. Yuru Yuri
18. Nobunagun
19. Sugar Sugar Rune
20. Onegai My Melody

haibane renmei
narutaru
noein
tatami galaxy
uta kata
break blade
c (pic)
cybersix
denpa teki na kanojo
paranoia agent
senyuu
sabagebu
makai ouji devils and realist
coppelion
texhnolyze
akb0048
sasami san@ganbaranai
uchouten kazoku
jinrui wa suitai shimashita
katte ni kaizou

Mirai Nikki
Higurashi
The Pet Girl Of Sakurasou
My Little Monster
Chuunibyou
Sola
Amnesia
Kamigami No Asobi
Brynhildr In The Darkness (pic)
C3
Sankarea
Maria Holic
Waiting In The Summer
Nana
Tokyo ESP
Bento
Princess Jellyfish
Blast Of Tempest
Kill Me Baby
Chi's Sweet Home

I can only think of 망가 xD
1. Inu x Boku
2. Higurashi No Naku Koro Ni
3. Noucome
4. Your Lie In April
5. Ao Haru Ride (Don't know how 인기 it is)
6. Kampfer
7. Steins;Gate? Maybe
8. Love, Chunnibyo and other Delusions
9. The Circumstances in my bathroom
10. Denki-Gai
11. Kotoura-san
12. Tonari No Kashiwagi san
13. Tonari no Seki-kun
14. Watmote
15. Sakura Trick
16. One Week Friends
17. Kids on the slope
18. Sunday without god
19. Locodol
20. Beyond the Boundary

1. Mahou Sensou
2. Nourin
3. Nisekoi
4. Strange+
5. Onee-chan ga Kita
6. Z/X IGNITION
7. Hamatora
8. Nobunagun
9. Witch Craft Works
10. Robot Girls Z
11. Ano Natsu de Matteru
12. Senhime Zesshou Symphogear
13. Aquarion Evol
14. Kamigami no Asobi
15. 메리다와 마법의 숲 10
16. Moretsu Uchuu Kaizoku
17. Tantei Opera Milky Holmes
18. Nisemonogatari
19. Nobunaga The Fool
20. Wizard Barrister

Nanaka 6/17
Special A
Princess Jellyfish
Black Rock Shooter
MM
K-On
Sore demo Sekai wa Utshukii
Kids On The Slope
Beck
Fractale
우주 Dandy
Bastard!
Bakuman
Little Busters!
Trouble Chocolate
Demon King Daimao
Tamako Market
Magikano
Mawaru Penguindrum
Nyan Koi!