Shugo Chara! (TV)

Buono!, the artist that sings this anime's intros and outros, was created specifically for this anime.

Suu likes to add "-desu" to the end of her sentences, similarly to Suiseiseki of Rozen Maiden, also by Peach Pit

Utau translated into english means "to sing"

On episode 16, when Zero starts the fight with Amu, the top card of the deck he is about to throw at her, is a Joker(Amu is the Joker).

The New Queen, "Rima" strongly reseblems, "Tsubasa" from 'Kare Kano(tv)'. Her character is even similar, to "Tsubasa's".

And it just so happens, that "Yaya's" baby brother's name is: "Tsubasa".

On episode 32, around 2:32 'Amu' imagines Nikaido-sensei asleep on his buisness trip. On his lap, is a book, or Manga. The cover has what appears to be "Gundam"(or just a Giant robot manga).

At the end of the last episode,(ep. 51) it shows Amu standing in front of a building. Part of the sign is hidden behind a tree, but what is visible says; "Dais".(Her 4th Shugo Chara).

In episode 7, Ami (Amu's little sister) wears a dress that looks quite similar to Kanaria's of Rozen Maiden, another series of Peach-Pit.

In episode 9, Amu imagines Nadeshiko's father doing a Fujisaki Blast (Ka-me-ha-me-ha, from DragonBall).

In episode 21, right before Nikaido-sensei comes across the boy reading the "My ROBOT" book, it shows him on his cell phone, which had a Robot charm.

In episode 32, 'Yaya' and 'Pepe' do a pose, which they refer to as, "Balance". This is a similar pose, which is the final step to a Fuzion-technique, from the anime series "DragonBallZ".

In episode 50 when Kiseki and the other Shugo Charas are thinking of their way to the Castle the scenes that follow closely resemble role-playing games (commonly known as RPGs) including their appearance and the whole setting in general