Here's a little 3-minute tutorial I created for our students that demonstrates how they can use a combined Creative Commons and Google Image search to find copyright-friendly animated gifs. The importance of attribution is covered.
And I'll be sure to remind our students to check out our Copyright and Creative Commons LibGuide for more resources.
And thanks to Google for adding this fantastic new feature!
Update: Google also added a 'Transparent' option, under Color. Even better!