what do you do before you play, practice, or rock out for the gig?  any stretching?  rudiments?  heck, jogging in place?

I always start by doing single handed things 8's or 4's in each hand (many reps) then progress into singles, doubles and all the paradiddle permutations. After this is done I like to do singles between my hands and my feet just to get the juices flowing throughout my body and to get my mind warmed up to the idea of including my feet.

rudiments, play, create.

I usually just rattle through some songs along to a personal CD player, and make sure i have loosened my hands properly so they dont cramp.

Sometimes, yes, I do feel more comfortable if I get to warm up some, but I don't really find it necessary most of the time.

I play some gigs where an extended warmup is just not possible.  Also, I frequently sit in at blues and jazz jams, and there's no chance to warm up at all.

I wouldn't want to open up with a 300 bpm burner with an extended solo, but other than that I'm ready to go when I arrive.

For me, it depends on what my playing application is or is going to be.  It also depends on how much time I have available.  

If it's a practice session, I warm up with wrist and finger stretching, followed by a couple of minutes of open/closed, open/closed double stroke rolls.  The rolls are started SUPER slow and the accent is placed on the first stroke of each double.  As the roll begins to close, the emphasis starts to fall on the wrists and forearms.  When I feel any tension during the close of the roll, I back off on the tempo and bring it back to a tension-less tempo, then slowly bring it back up again until I can completely close the roll, and hold it for at least 30 seconds without any tension.  Then, I slowly open the roll back up and make sure I'm still accenting the first stroke of each double all the way back to the original, SUPER slow tempo.  Next, I repeat the above double stroke roll except this time, I accent the second stroke of each double.  This places emphasis on warming up the fingers.  If I have time, I'll do the same thing with the single paradiddle and its three inversions.  Finally, I'll play a buzz roll at a tempo where it sounds good, and hold that for 30 seconds to one minute, focusing on the sound and even-ness of the roll.  At that point, I'm not getting any warmer.    If I do all of the above, it generally takes about 20 minutes.    

At a gig, I usually don't have the opportunity or time to do a warm-up with sticks so I just make SURE I do some wrist and finger stretching.  The gig itself, also determines the nature of my warm-up.  For instance, if I'm playing a one-hour, high energy rock show in a large club where I'm playing hard and/or loud, all I really need to be concerned with, is being loose and relaxed, so stretching is all that I would do in this case, to make sure I don't cramp up or hurt myself.  Or if I'm playing at a Sunday morning worship service at a church, where I'm playing quietly, I probably don't do much of anything except maybe stretch my hands about 30 seconds before I start playing.  

As I get older, I find that the most important way to 'warm-up' before any type of performance, is by stretching and mentally preparing, by thinking about what I'm about to play.  Warming up with sticks becomes less and less important.

I do the same thing.  My hands & wrists give me lots of trouble!

As far as pre-gig excercises, the only thing I do is spend about 5min playing all the surfaces and re-adjusting setup.  Once thats done, I start pacing the floor like a caged cat.  

I do some form of a yoga before I play.  It may be several hours before, but the stretching benefits are felt all night.  If I can, I run through the 20 minute warm-up that MD published as part of its special issue on Technique a few years ago.  It's simple, efficient and helps set the mind at ease.  If not, I try to do at least 2-10 minutes of singles and doubles on a pad, pillow, speaker box, snare w/towel, etc.

As for practice sessions, I do a a proper warmup (see above) and also a cool down at the end of the session.

funny enough, if i dont drink enough water, i get a cramping sensation around my bass drum leg's shin.

and yet, its amazing how well my leg feels when i'm hydrated.