You know about the P90X fit test, and I've previously posted about the U.S. Marine Corps Fitness Test. But for those of you who are curious about how you'd fare on other tests of physical fitness, check out this article by Sam Murphy in today's Guardian.
In it, Murphy discusses the U.K.'s National Fitness Test, a free online test that purports to measure your "strength, aerobic fitness, flexibility and 'shape' (weight, height and body measurements), giving you an individual score for each component as well as an overall 'age.'" According to the article, the cardio portion of the National Fitness Test is modeled after the Harvard Step Test and the Canadian Home Fitness Step Test -- both "submaximal" tests that don't require you to reach exhaustion, but instead gauge your aerobic fitness level using your heart rate response (similar to the "Heart Rate Maximizer" part of the P90X fit test).
From this video, it's clear that folks with jelly legs won't be able to get through this test. So for people with weak legs, the article suggests the Rockport Walking Test as an alternative.
On the flip side, if you're looking for a "maximal" test that pushes you to your VO2 max, check out the Multistage Shuttle Test (a.k.a., the "Beep" or "Pacer" Test).
If you're looking for a nice, brisk run instead, a "slightly less daunting alternative is the Cooper Test -- a 12-minute run in which you cover as great a distance as you can, or the 1.5-Mile Run, in which you aim to complete the distance as fast as possible." Note, however, that while "such tests are useful for fit, healthy, active people," they "may be too challenging" for couch potatoes.
Lastly, while it's not included in the Guardian article, all of you "Man vs. Wild" types should check out this circa-1926 fit test by strongman Earle E. Liederman -- it features five fitness benchmarks and is based on the premise that you need to be sufficiently fit to save your own life in an emergency.