Water, the cellphones worst enemy. There are many urban legends if you get a bag full of rice, and throw your phone in it the rice should absorb a good deal of the water. Or, you could get the Wet Cellular Phone Emergency Kits.
The bag contains some sort of super-absorbent material that, much like the rice, will take the water out of your phone. When disaster strikes, you simply tear off the top, toss in the phone (or any other small electronic device) and zip it shut for a couple of days. Not bad for $10. I could save you hundreds.