Looking for clips [young versions of characters]

[CorpseGoddess]

Ah! My Goddess has Urd as her younger self. And you could always use the chibi versions of the three from The Adventures of Mini-Goddess.

[HalOfBorg]

How did I not think of Dragonball GT? The bulk of it is Goku turned into a kid.

[Samcyxk]

Tsubasa: Reservoir Chronicle has clips of younger Syaoran and Sakura in it.
Also, Pandora Hearts has lots of clips of young Gilbert

[EkaCoralian]

Ooh, and Xam'd! Nakiami takes a step into her past when she's speaking to the old Sannova lady, so she's really young. I think thats episode 24 or 25.

[LopezAMV]

I'm surprised no one has mentioned Naruto. It's packed full of flashbacks and whatnot for just about every character in the show lol.

But then again not everyone likes Naruto, so here are a few others:
Fullmetal Alchemist: There's quite a few good clips towards the beginning of the series. Same for Brotherhood.
Code Geass: Young Lelouch is pimp.
Eureka Seven Pocket Full of Rainbows: There's some clips of a young Renton and Eureka somewhere in there.
Darker Than Black: Towards the end of the main series there's some clips of the main character as a kid.
Gurren Laggan: littlle Simon big Simon
Ga-Rei Zero: Series is only 12 episodes long so it shouldn't be hard to find those clips.
Negima: Last few episodes
Evangelion: little Shinji and Asuka are mentally disturbed and possibly mentally challenged xD
One Piece: I only saw the first 20 episodes back when it was being aired on Toonami, but I remember there was some in there.

Good luck!