Albatron announced a couple of months ago the first AGP to PCIe bridge card.
Codenamed "ATOP", the card allows you to use your AGP-8x card with PCI-E mainboards. The AGP-8x card simply piggybacks on the ATOP card's AGP-8x slot located on the top edge. The ATOP card is then plugged into the mainboard's PCI-Express slot. The only other installation requirements are replacing the bracket on the AGP-8x card with an ATOP bracket and installing the appropriate driver.
The ATOP bridge card is currently supporting only Nvidia's solutions:
The ATOP bridge is curently available in Japan for 3,000 YEN, about $27. In the rest of the world you will be able to get these cards bundled with some of the Alabatron's AGP cards such as the AGP6200AL.
Albatron offers the oportunity to - unfortunatelly Japanese only- owners of high end AGP cards such as 6800 series to rather spend $27 and re-use their still great gaming card in their new PCIe enabled motherboards. Hopefully we might expect this solution to be implemented in future Nvidia's graphics cards kits.