Ive got an aquapac as above. I use it for my IPhone and havent found any problems with the plastic being sticky. That being said, if I am trying to send a lengthy email or text then I will likely be going slow enough that falling overboard or dropping it shouldnt be an issue so would normally take it out the pouch. However, I do use the iphone for gps while afloat and have always managed fine!!
I used to use it for my N95 as well and worked well but was a little fiddly to slide the slider. However, imo, the most important thing is that it keeps the phone dry for when you do need it as none of them are great if you try and talk with the phone in them!
Ive put a carabina on the end of the string as well so I can clip it onto my belt loop as I am paranoid about dropping stuff!