Mensa—the club for people who know they're smarter than you—is offering its home test for free during the month of January. It's an IQ test that takes 32 minutes to complete and at the end it'll tell you whether you're Mensa material. Although acing this test won't get you admitted to Mensa—that test has to be taken in a controlled environment—it's a really good approximation, and a good score would certainly be good enough to declare yourself a genius, at least to your dumb friends.
This test takes place on a computer, but the actual Mensa test is on paper. If you want to seriously prepare for a Mensa exam, the written test is still $18. You don't have to be a genius to figure out how to take the test—you input your address and email, and then they'll email you a code that gives you access to the virtual test center.
Mensa is an organization that's been around since 1946 and its primary objective is to identify high IQ individuals and nurture them. The primary requirement is that you have to have an IQ that's at or above the 98th percentile. Those odds aren't bad—they're about one in 50. Once you're a member, you get to attend exclusive gatherings and discuss things like science, philosophy, and your favorite websites. Who said smart people don't have any fun? [Mensa]