No, there was an AGP to USB card.
The HP rp5000 Point of Sale system was launched circa August 2003 and includes this unique AGP card:
The rp5000 has the (half-height) AGP card installed vertically and two PCI slots installed horizontally using a riser board, allowing the use of two full-length PCI cards on a half-height system. The AGP card is placed flush with the rest of the motherboard I/O, slightly disguising it.
This card provides three PoweredUSB ports used to connect and power barcode scanners and receipt printers for a POS setup. The two blue ports provide 12V power and the red port provides 24V power (power provided via Molex connector). The nine pin internal USB connector on the top of the card connects the 12V ports to the motherboard's internal USB header with an internal USB cable. However, as can be seen on the back of the card, pin 4 of the card traces towards the 24V port, meaning the card is using the USB connection provided by pin 4 of the AGP spec, as linked above, to connect that port. Pin 1 side B of the AGP port provides USB overcurrent protection, but it is left unwired, as PoweredUSB has its own OCP. The rest of the AGP pins are also left unwired except the ground pins, and there's reason to believe the AGP port on the motherboard is also not fully wired, as the rp5000's hardware reference guide states "An AGP card will not work in the AGP slot."
So why use AGP if the only thing you're using from the standard is the USB connection for only one USB port? A later model from the line, the HP r5700, used a PCI card for their PoweredUSB ports instead, so a half-height PCI card could have been used instead.
The only reason I can think of is that there must have been only four USB ports available from the motherboard's USB controller, as the rp5000's motherboard has two USB ports on the motherboard I/O and one internal USB header for the two 12V ports. Given this limitation, HP had to create a card that would also provide USB support to a fifth port. HP could have done this using PCI, but that would require purchasing another USB controller chip, so they decided to use the single USB port provided by the AGP standard instead.
In fact, the rp5700 PCI card didn't use the PCI interface with a USB controller to connect its USB ports either, as all its data pins are left unwired. Instead, it uses internal USB connectors for its four ports, but its motherboard supports two internal USB headers.
This is a super unique use of the AGP port, and the only other devices that I know of that actually use the USB connection are the Apple-specific versions of ATi and Nvidia AGP video cards that supported the Apple Display Connector.