little monster boy and girl: Mo and Mia.
The pattern for Mo (the boy) is free on her blog: Ami Loves Gurumi.
Go check-out Karin's blog: it's full with stories and free patterns.
The pattern for Mia is not free: it's published in a book called "Fun and Easy Amigurumi", available on Amazon.com and Amazon UK.
This book has just been made available in German on Amazon.de :)