A Subscription worth paying for it pays it off in no time.
Yes, there are a few free sites where you can get clip art, animation and some other pictures for your blog posts - to look more attractive. However, if it has any copyright violation, you are in trouble. You need a subscription based produce - like PresentationMedia - to protect your own interest and at the same time, give a new look to your blog posts. Based on other reviews, this looks like a product worth trying. Good Luck.