Here's a great site for HCMC street maps called DiaDiem. (Thanks Carey for the pointer.) It beats the crap out of Google Maps. It has the best collection actual street addresses that I have found in an online map for Vietnam.
Second runner up is Anan Vietnam, which mainly focuses on restaurants, but has a decent online mapping facility.
If you just want satellite maps, then you can stick with Google Maps or may want to go with Google Earth. But if you're trying to figure out where you're headed before getting into a taxi, Dia Diem is a great place to start.
It has an English version, but you'll still need to understand some Vietnamese if you're going to to search. All the categories are in Vietnamese, even after you switch to English. We all know Khach San means Hotel and Nha Hang means Restaurant right?