I bought a pretty nice stereo system this past summer, my third system in the 3 years I have owned my Jeep. In those 3 years a put barely 10,000 miles on it so I didn't use it much.
Anyway, I did NOT want to pop this stereo system. When I took the old one out and got into the dash, I noticed that there is a bracket right above where the stereo goes. It has a hole drilled in the middle. I cut myself a piece of scrap aluminum that is approx 2" wider and longer then the stereo, drilled a hole in the center, and bolted it to that bracket. My stereo now has its own cover that shields it from dropping water. I also took some silicon and sealed the gap between the plate and the dash so no water drips down the front, and ran two lines of silicon on either side so that any water that drips onto it runs out the backside.
It's been 8 months and I have not popped the stereo, even though some water has been getting in. This quick fix worked quite well.