In the
US Navy, being that we were typically surrounded on all sides by lots of
salt water, we had to recover devices that either fell overboard or had the
overboard visit the ship in the form of a huge wave.
Believe it or not, fresh water baths are the best way to recover electronic devices, as mentioned by VXO in the previous writeup. There are a few additional items I'd suggest to do.
First off, when you soak a speaker with a paper cone, you can sometimes save it. Remove it from the device and apply a blow drier to the cone, front and back. With any luck you've kept the liquid from invading the coil area. To save the paper cone itself, after drying it apply either rubber cement or clear nail polish. In a pinch, spray silicon can sometimes do if it's coated in layers. I've seen folks use yellow spray paint with great success. What you're trying to do is support the paper and keep it from tearing.
Having it just dry for a while may work if you're in an exceptionally dry environment, but water tends to wick up under transistors and capacitors quickly and stay there. I'd say most items are destroyed by shorts on the transistor legs or popped capacitors. After letting the device dry as suggested above, get a can of compressed air, some electronics tuner cleaning spray or some nice yummy trichloro-triflouro-ethane to spray under the legs of the capacitors and transistors. Then take the time to blow out any transformers, since water will wick in and stay for a while.
Clean any exposed contacts with a red rubber eraser, especially around the batteries. Do not put a soaked battery back in the unit, get new ones. They will typically leak within 30 days, getting grotesque chemicals all over your (now) nice clean boards.