I had high hopes when MacSpeech Dictate was originally released. Using the same engine as Dragon NaturallySpeaking, it converted users' speech into text. Unfortunately, many of the reviews I read concluded that it was a great start, but there was more work to be done before it was good enough to be used everyday.
Well, version 1.5 has just been released, and the reviews are much more positive.... Review: MacSpeech Dictate 1.5 | GottaBeMobile.com MacSpeech Dictate 1.5 Review | MacSparky
Once I upgrade my 1.66GHz Mini to a 2009 model, I think that now's the time to get hold of a copy.