Good post with valid questions...

My quest for a durable water resistant phone is due to my work with the Candian Coast Guard Aux. Most new phones are very easily killed by water. I've even killed a phone inside a drysuit due to moisture build up inside.

I've used the OMNIseal pouches and they work well for Razors and the like. Good protection, but no funtionality obviously when inside. These are the pouches that the small AMK kits come in.

The Casio phones are great and the older version actually meets some pretty good Mil specs. They can only be used on Verizon network however. Maybe in the future, with Verizon's announcement of opening up their network, we might see a version with greater compatability with other networks.

Most "Candy bar" phones are inherently more durable than flip phones from an over use, dropped it on the deck again, point of view.

The phone I am using now, and have yet to kill (touch wood) is a Nokia 5500. It's doesn't meet any Milspecs but is very well built and protected. It is also a full featured "Smart Phone" with all the stuff you want from a blackberry and the like. The trade off is that to be small and durable it has a small screen though.
There is a Russian cell phone test site that torture tests phone and it did very well. Also on YouTube there is a video of it funtioning in a pint of beer.

If you don't need a smart phone, Siemens makes some durable phones (M71, M81)
Older Nokias like the 5140 are very durable and can even have a GPS module tacked onto it.

My thoughts are generally worth exactly what you've paid for them.

Jenks