Eskimo Kisses in School hallways by Squishy_xo:

Summary: A variety of one shots all set in the same ‘verse. Occasional Kid!Klaine. They’ve been boyfriends since they were eight and best friends longer than that. This follows little fluff happenings in the AU popular!Klaine lives. Rated: language and suggestion

 http://www.fanfiction.net/s/7408563/1/

Swing Sets and Sandboxes by beautifulwhatsyourhurry:

Summary: Kurt Hummel is 7 years old. He makes a new friend, little Blaine, on the playground one day. This is their story.

http://scarvesandcoffee.net/viewstory.php?sid=27

Kings of the sky by heartsasmagnets - G

Summary: Blaine Anderson notices a sad and lonely boy on the playground and decides to spend recess with him. 

http://heartsasmagnets.livejournal.com/17961.html#cutid1

Belly aches and exploding smiles by heartsasmagnets - PG

Summary: Blaine Anderson is the only person Kurt Hummel invites to his seventh birthday party. Sequel to Kings of the Sky.

http://heartsasmagnets.livejournal.com/18881.html