Unfortunately, once it's in there, there's no getting it back out again - no matter how long you stare at the pot and curse under your breath!
The best thing to do is add more ingredients to the dish to dilute the salt. You might not end up with your original dish, but at least it will be edible.
Another cup of stock will thin out a thick soup or turn an over-salted stirfry into one. A handful of grains or noodles will absorb much of the salt and even taste better for it. Adding more vegetables is yet another option, and a good one if you want to keep the dish as close to the original as possible.
Do you have any other tricks for fixing an over-salted dish?