PCI video cards are still pretty plentiful at stores here, and most of it is due to machines without AGP slots. Only recently did Intel really start pressuring motherboard makers to toss in an AGP slot on all boards, so many cheap computers with integrated video didn't have AGP slots.

I'm still bitter over AGP. Yes, having a dedicated bus for the video is awesome, but PCI technology in home machines is suffering stagnation. Instead of AGP, I would have preferred a dual bus PCI setup, with at least one 64 bit 66mhz slot for video. Thats probably enough to take care of video card demands on the system, and with the advantage that if integrated video was used, an extra slot would be free. I see no reason to have a special slot for add in cards for any reason beyond the reasoning of PCI-ES.

(And before someone asks...)
PCI-ES is a standard for array controllers. Instead of having the controller contain the SCSI cable connectors, the motherboard has them. Why is this useful? Well, all PCI-ES systems have two of these slots, allowing for redundant array controllers with no need to swap cables or mess with duplexing on the back of the drive cage. The slot is rather complex, it has enough pins to connect the PCI 64 bit part, plus 3 68 pin SCSI connectors. It's longer then 64 bit slots, and is also two layers deep, similar to AGP cards, but not staggered.