My warm up has evolved a little. Back in 2009 I documented my warm up here. This in itself was was based upon an earlier post from 2008. My warm derived from the book 'Stretching Scientifically'. I have since made some small additions to the routine.
The basic warm up has two parts; Rotations and Swings.
I rotate clockwise and counter-clockwise my wrists, shoulders, chin (not the neck), hips and then knees. Usually 10 in each direction (or two sets of five).
The swings are controlled movements of the limbs. Starting with the arms, I swing my arms back and forth in an exaggerated marching style. Then, after completing 10 reps, I move on to swinging them to the side at various angles.
After this it is down to the legs. I swing them to the front for ten (goose-step style), to the side for ten, and then to the back for ten. Each leg is obviously swung one at a time!
The new additions are also leg movements. I complete a set of squats (elbows inside of knees), side lunges, front lunges and then twisting lunges. These ideas were taken from LGKF.
As luck would have it I recently stumbled across a very fine article on StrongLifts that covers most of these kinds of lower body stretches and offers some interesting alternatives. The article and associated YouTube clips are rather informative and worth looking at. My one caveat is that the leg swings are way too ballistic for my liking. I prefer to 'lead' the limb rather than swing it. I also start well within my ROM and only push on the last couple of reps. Other than that, there are some useful variations to develop hip flexibility which I shall be using.
The only other addition to my warm up is a backflip - which really is a 'test' that I actually am warmed up. This probably indicates I am mentally ready as much as physically ready as I cannot really throw one unless I am in the zone!