Air Force PFT
1.5mi Run
1min Push-ups
1min crunch/sit-up
Yeah this is the one I was subject to for most of my years in, too. There were some really goofy years in the '90s where the AF implemented a cycle ergometry test... Don't even get me started about that one.
The problem for most people with the minimum type test (and yes people still have trouble passing it - they make up some of my personal training clients now) is that they don't know how to train for it, or really what the objective is. Think about the message of a test. "The military wants me to be able to do X, Y, Z. Therefore I train X, Y, and Z as they are tested." Ideal? No, not at all. The AF members go out and run a mile and a half as fast as they can time after time, or do a max set of push ups or sit ups, and that's their "training." It doesn't get them to the real goal, which is a basic standard of health and fitness.
Not to mention this -- a test sends a message: "Being able to do X, Y, and Z is important to being able to do my job in the military. It must be, because I'm tested on it." When this doesn't make sense to people (as would probably be the case with a crawling test), all sorts of ridiclue and disparagement runs rampant within the ranks.
@mprevost makes a great point about logistics. When you have to conduct several thousand tests per week as they do at basic training, and then to a lesser degree, everywhere else at least once per year for all members, it's a huge consideration.
The other important aspect is objectivity. You have to be able to train the testers in all locations and units to objectively evaluate whether someone has passed the test. Lots of possible tests can be elminated due to too much subjectivity.
As for ideas for the actual tests themselves, I don't have too much input... lots of good ideas above, but if the were all put through the reality wringer the end results might be the tests that already exist. I do like the idea of the two-tier system though, and that's pretty much what exists in the Air Force now, with the vast majority getting the basic test, and the battlefield airmen (special ops career fields) getting much tougher tests that include swimming, longer runs, etc.