What adapters work from Thunderbolt to HDMI

The Apple mini-DisplayPort to VGA or HDMI adapter terminates the Thunderbolt chain where it is connected, so until Apple released new MacBook Pro with two Thunderbolt ports (similar to the iMac that has two ports) then you will only get one video signal from the device through the Thunderbolt port.

You may find an inexpensive USB to VGA solution to get around this limitation. Initially they were slower, but the newer ones are getting much faster and the software much better. You can then put the most important content on the Thunderbolt port and have the secondary display served over USB.

Should a Thunderbolt adapter come about that drives two displays, I'll update the answer, but nothing has been released (or even rumored) even though it's clearly something the protocol could support.

I like this knowledge base article for the clear deprecation of which Macs support two Thunderbolt displays and which ones only support one.

• Apple Thunderbolt Display (27-inch): Connection options for Thunderbolt Macs

You cannot run VGA from the HDMI port the way you have it set up. You need a direct HDMI->VGA converter. The reason is that HDMI does not output analog signals. The cable head actually has a digital-to-analog converter chip in it, but your HDMI<->DVI adapter does not. So even though the DVI<->VGA adapter fits, the analog pins aren't actually connected.

Technically, the HDMI<->DVI converter you're using was manufactured incorrectly. They should have used a DVI-D connector, but they used a DVI-I instead. A VGA adapter will not fit onto a DVI-D connector, but a DVI-I connector will accommodate anything.