You're right, the usual BMI test is a total farce. Puts most athletes in the obese category. I think it was designed for sedentary couch potatoes who won't turn off the tv long enough to take a real test.
Some more reliable BMI tests require that you also enter measurements from wrist, forearm, waist, etc. which makes much more sense, and has a more accurate BMI result. But I've heard that skin fold tests are one of the most accurate ways to test BMI, and you can get this done at most gyms.