On my Inc I had Vlingo and loved it. Mainly because the speech-to-text worked a lot better than stock.
Now that Swype is pre-installed on this phone I'm making myself try it for a week or two. If I decide I'm not with it, I'll download Vlingo again.
Vlingo used to be $10 but it became free a few months ago.
Voice to Text Applications Powered by Intelligent Voice Recognition | Vlingo
specifically Android Voice to Text and Voice Recognition Apps | Vlingo
Note that it has a keyboard but it also allows you to control your phone in many ways by voice, for example texting while driving can be done entirely with your voice.