[GBH2]

iGuidance 4 has:
Text to speech (announces street name in voice);
Extended POI listings (6 millions);
Pre-generated map file for entire N. America (1.3GB) which can be stored on your storage card.

I haven't upgraded to version 4 yet but I have found IG v2.3 very good at getting you where you want to go.

I have read that OnCourse Navigator is good too, but no TTS and you have to use their microSD card - you cannot transfer the map data.