Usually I will just cook it and then tear it to pieces using two forks, but this is still pretty time consuming. Are there any secret ways to easily do this?
Once it's cooled down some, I switch to using my hands ... expecially as it helps to find any bones, globs of fat, etc. I find it goes much faster, particularly if you're dealing with anything other than boneless breast meat.
... but it shreds easiest while it's still warm, so if I'm doing a fair bit, I'll break a bit apart using forks, let that cool, break some more apart with a fork, then shread the first bit before it cools too much, repeat. (so basically, I have one set broken down somewhat to cool faster while I'm shreding an already-cooled off bit).
update as justkt mentioned, the cooking method matters -- roasting and other high heat methods are going to cook the outside faster than the inside. I typically poach my chicken if I'm going to be shreding it -- bring water to a boil, add chicken, bring back to a boil, turn to low, then leave for an hour or two ... the low temp gets it all nice and tender, while the boiling kills surface bacteria.
I recently picked up a pair of Bear Paw Meat Handlers and they actually work quite well for this if you can't wait for the meat to cool down. Hope this helps someone!
I ended up purchasing some insulated latex cooking gloves which allows me to use my hands even when it's right out of the oven. This is the best method I have found by far!