I often spent time just searching other stampers sites for inspiration to create a new card. Here are some of the favorite kid's cards that I found...
An adorable "Bookworm" bookmark from http://latenightstamper-stampandscrap.blogspot.com/
This Lego card is from http://scrapstampandplay.blogspot.com/
A simple but sweet ladybug card from http://aedesigns.com.au/
Here's a cute "Fox and Friends" card from http://www.mjalbright.wordpress.com/
This one is a cute Santa card from http://www.anewinkonlife.com/