HDMI uses the DVI-D video signal. DVI-A is the same as VGA. Generally DVI graphics outputs (both dual and single link) output both DVI-D and DVI-A, hence you can get the cheap DVI->VGA, DVI->HDMI converters (minus audio), and HDMI->DVI-D.
Not entirely sure how HDMI to VGA (or VGA to HDMI as the title suggests?) without an active adapter could work (wasn't aware HDMI had some standard thing like the Display Port DP++ thing for passive DVI/HDMI adapters, and even then you need active to get VGA? But looking around a found some people selling cables?)