The "Sora no Woto" reference count...

I'm just going to keep a list of every anime I can link with this series:

Elfen Lied: Opening animation visual style
Madlax: Opening music *
K-ON: Character designs for Rio, Felicia, and half of Katana and Kureha's.
Serial Experiments LAIN: 1/2 of Kanata's character design.
Haruhi Suzumiya: Noel's character design.
To Aru Kagaku no Railgun: 1/2 of Kireha's character design.
Haibane Renmei: Pacing

*I said .hack earlier. This is much more similar...