So, I went to one of my favorite sites for questions like this - Free Technology for Teachers. I've shared other tips, tricks, and ideas from this blog before and I highly recommend you bookmark thesite, add the blog to your favorite reader, or follow Richard onTwitter or your favorite social media site.
And, after doing a quick search on his site, I came up with this blog post:Free PowerPoint Templates for Teachers and Students. I started browsing through Slide Hunter and found some fun new templates to try. I created a free account and downloaded my first template in under 15 minutes. Don't be surprised if you see something like this in an upcoming presentation from me.