Embedded.com - An introduction to USB development.
Everything USB - News and product reviews on both USB 1.1 and 2.0 peripherals and adapters. Also includes a FAQ and USB 2.0 driver update.
Macspeedzone.com - USB port speed compared to other port speeds.
Spread Spectrum Scene - Provides tutorial, information links, and recommended reference books on the Universal Serial Bus.
Universal Serial Bus Implementers Forum - Current revision of the USB spec with all available device class documents, whitepapers and also the compliance workshop checklists.
USB and USB 2.0 Forum - Offers the ability to ask questions and get answers, tips, tricks and experience.
USB Central - Information, tools, and links to material about the Universal Serial Bus (USB).