Dynamic Stretching & The CrossFit Warm-Up

The beginning of you warmup should include 5 mins of dynamic stretches, gradually increasing the range of motion and intensity until all joints and muscles are warm. Here is an article from James Madison University showing some dynamic stretching examples. Enjoy!
Dynamic Stretching

The "official" CrossFit Warm-up is in the April 2003 CrossFit Journal.

3 rounds of 10-15 reps of
Samson Stretch (do the Samson Stretch once each round for 15-30 seconds)
Overhead Squat with broomstick
Sit-up
Back-extension
Pull-up
Dip
Note that for a workout that's dip or pullup-centric, you might want to do something else in the warmup.

Here's a video of Greg Amundson's stretching routine. Greg was one of the original Santa Cruz CrossFitters and an incredibly gifted athlete. Matter of fact, he was one of the trainers at Ron P's level one CrossFit Certification this past weekend.