Taking care of the only habitable planet we've got for the foreseeable future seems like an excellent idea. I'm with The Tick: "You can't destroy the Earth! That's where I keep all my stuff!" It's also where a lot of the cool geology is. I mean, yeah, there's plenty of that on other worlds, but it's kinda hard to get to.
So I'm happy to accede to Wendy Kirwan's request to give the kars4kids Earth Day site a mention:
I know you’ve written about Earth Day in the past, so I wanted to make you aware of a really great resource that we’ve created here in honor of Earth Day 2013. It’s chockfull of interesting tidbits and historical info about Earth Day. Even better, we’ve included so many suggestions of things you can do on Earth Day (like building a compost bin or turning an old t-shirt into a reusable shopping bag) and ways to take action for our Earth (purchase or make your own green cleaning products would be one example). We’ve even got an embeddable infographic/timeline that is just awesome. Check it out: http://www.kars4kids.org/earthday/
I did, and it's definitely worth your time, so swing on by. A lot of those activities will be fun to do with kids. If you have a website, you can grab their timeline too. And yeah, I know, a lot of people think individual actions aren't all that important, but folks: there are seven billion of us. If we all do just one thing, just one, to help keep our planet habitable, that's a hell of a lot of impact. So don't despair if all you can do is small stuff. It adds up.