Six ways your iPhone can make you smarter (screenshots)

Channel your inner Cliff Clavin and impress your friends with an endless stream of interesting facts. This free app serves up more than 10,000 of them ("Men are 6 times more likely to get struck by lightning than women"--who knew?), any of which you can share via Facebook, Twitter, or e-mail. Just shake your iDevice (or swipe the screen) to move from one fact to the next. This is the perfect app for trivia buffs and knowledge seekers alike.

I'm terrible at geography--but I'm getting better. Thanks to Google Earth, I can quickly and easily zoom to any point on the planet, complete with satellite imagery, Wikipedia entries, geo-located photos, and three-dimensional viewing. When you find yourself wondering, "Where the heck is Haiti, anyway?", this is the app you use to educate yourself.

Need to know how to fix a leaky faucet? Or avoid red eye while snapping photos? Maybe you're looking for some hip-hop dance moves. Whatever you're after, Howcast delivers how-to videos wherever and whenever you need them. You can view featured, recently added, and random videos (just give a shake), or search for any topic.

Who says college has to be expensive? Apple's iTunes U offers individual lectures and complete courses (mostly audio, but some video as well) from the likes of Cambridge University, Stanford, and Yale. Subjects range from business and engineering to social sciences and teaching. Best of all, you don't have to spend a fortune on tuition: everything's free.

Say what you will about Wikipedia--it's an invaluable go-to reference for just about any subject. And unlike most encyclopedia apps, Wikipedia Mobile is free. It's an official companion to the Web-based version, which I often liken to what Douglas Adams envisioned in his "Hitchhiker's Guide to the Galaxy" series: a "standard repository of all knowledge and wisdom." All it needs is a nice splash screen that reads, "Don't panic."

The ultimate tool for smart-people-in-training, self-proclaimed "knowledge engine" WolframAlpha answers questions relating to society, astronomy, mathematics, money, geography, and much more. It's ridiculously cool, startlingly effective, and a bargain at $1.99 (especially in light of its $50 introductory price back in 2009).