When I commute, I like to use my Blackberry and the Endomondo application to track my miles but on the Fredmobile, I can't stand riding with a top tube bag. I have tried a few and none of them worked out. Then I found this dry bag from Topeak and I just new it would do what I want it to. Not to mention it allows me to mount it on the stem.
It's tight fit for the Blackberry and in fact I had to cut the sides in order to get it out so it's no longer really a dry bag anymore. It will still keep water off the Blackberry but it means that I just can't go swimming with it. It worked great.