One of the important features of USB OTG is that the standard does not require a host PC in order for the devices to communicate. USB OTG devices, known as dual-role peripherals, can act as limited hosts or peripherals themselves depending on how the cables are connected to the devices, and they also can connect to a host PC.

Everything USB
Learn about the different flavors of USB and communicate with the USB community.

USB On-The-Go
Developer’s page for USB OTG from Usb.org.

USB OTG FAQ
An FAQ from Usb.org.