In the last 5 years or so, USB has emerged as THE standard power source for portable electronics, and a host of other low powered devices.
Today, I happened to stumble upon an early example called the USBHV on eBay. The USBHV is a USB powered high-voltage source from EMCO High Voltage, released in 2009. The USBHV was positioned as a compact, USB-programmable (and powered) high-voltage source for research use. From what I’ve been able to tell, there was actually a line of products, differentiated by positive or negative voltage, and maximum voltage, with the option of 200V, 500V, 1000V, 1250V and 2000V at up to 1W of output (USB can deliver 2.5W). My guess is that they had a board with a USB controlled AD/AD converter for setting and reading back voltage, and mounted one of their standard high-voltage power modules.
The present-day EMCO High Voltage website only has one tiny reference to the product, a link to a generic form for information on off-catalog products, so no datasheets, manuals or software.