jenny foltz has quite a few really cute applique-sports theme patterns- here's her link:
www.jennyfoltz.com
i've used jenny's for a football & cheerleading quilts in the past-they are great patterns.
also, coloring book pages make great applique patterns- they are generally free & copyright free
there is also a book called - 'quilts for kids' which has snowboarding, skating, volleyball, i can't remember them all- but it has a nice variety of sports related applique quilts.