Mate, here, the best bar in my book and probably the first expat run venue by a compatriot mate of mine (not to advertise it too much), is Nr5 Bar.
They have daily happy hour (Mo-Su) from 3.00-7.30PM
Happy Hour at Nr5 means, free flow tap beer, incl Heineken, Tiger, San Mig and Saigon beer, regardless how long you're there, Happy Hour is charged at a flat rate for 170'000 VND (around 10 Aussie $) and needless to say, there's quite a few Aussies among the Happy Hour regulars!