Most of the running armbands for the iphone require you to remove the device from one case and enter it into another. After doing this daily for months, something breaks. After going through about 4 arm bands, I finally found a unique solution from a company called Marware. Their Sports Shell is actually 2 products; an arm band and a case with a kickstand that allows it to stand up on flat surfaces.
The kickstand part clips into the arm band and allows you to run with ease. I am not comfortable enough with myself to clip my phone to my belt, but I find it extremely useful to clip the phone to the inside of my pocket or to display on my desk. While it cost around $50 on the manufactures website, you can get if for $20.00 from Amazon.com.
Running in the Rain
Two football seasons ago, I drove in from New Orleans and hit the lakes at 5:30am. Around 3 miles into my run with 3.4 to go I got hit by a torrential down pour that I knew was coming. I had not run the lakes in 4 months and I knew I would be to exhausted on Sunday. After my run, I spend the 6 hours at the Varsity with my iphone in a bowl of rice. It did not make it. Now, I check the weather and look outside before I run. If I see there is a chance of rain, I will switch to the armband I use in the pool.
The amphibix waterproof armband will prevent a drop of water from hitting your phone. I also have the underwater headphones but I only use those when I swim. I do have to remove the Malware case to use it, but it is better then ruining a good phone. The armband is bulky but I stop noticing it after the first mile.