I used these USB serial interfaces almost everyday to interface with boards I'm hacking around with. This board is based around the CH340G, a cheaper alternative to the common FT232R. FTDIs business practices have been more than a little shady lately and it feels like time to move to a alternate platform.
Drivers are available for MacOS, Windows and Linux. I mostly use these boards under Linux, where certain kernels have builtin support.
The board supports 3.3 and 5v signaling.