There's even more to that. If you ask for a credit card cab, the person running the line will try to find the first cab that will take credit cards. This will sometimes be a cab on its way to another terminal. Since T1 is the first, they are likely to pick up T2 and T3 destined cabs for T1 people. (A cab driver explained that he would like to grap T3, that way he has high odds of somebody on the way wanting a credit card cab, thus saving a wait at the terminal.)

A few other cab tricks - when T1 is a zoo, T2 is usually pretty quiet. If there are huge lines at all domestic terminals, a free train ride to the international terminal can usually unearth some cab drivers who have been waiting a while for passengers. (And, it will save a few dollars on cab fare, as well as bypass the traffic jams...)

And then there is the L. I've used it as a nice means to bypass traffic on my way back from a 'delay delay CANCEL' night at O'hare. And since it even works for catching Zs.