Most bookshops in Vietnam stock a good range of maps. A must for its detailed road maps of every province is the Viet Nam Administrative Atlas, published by Ban Do. It is perfect for cyclists or motorbikers looking for roads less travelled and costs 68,000d.
Ban Do also publishes reasonable tourist maps of HCMC, Hanoi, Danang, Hue and a few other cities. Unfortunately, maps of smaller towns are practically nonexistent. Most of the listings mags produced in Vietnam have good city maps of Hanoi and HCMC, and there are a couple of good hand-drawn 3D maps of Hue and Sapa available from Covit, a local publisher.
Vietnamese street names are preceded with the words Pho, Duong and Dai Lo - on the maps in this book, they appear respectively as P, Đ and ĐL.