Samsung Galaxy S 2 voice talk
I find this feature really useful especially when I'm driving. I can just speak what I want and my Galaxy S 2 will do it for me.
Another feature I forgot to mention is the 'Drive mode'; When this is activated any message or call will be announced. ie when I get a text my Samsung Galaxy S 2 will say you received a txt mssg from "___" whom ever it is...It also says "__" is calling you.
I find that the navigation on this phone is a whole lot quicker than my TomTom.