I've seen, but not fished with, rods that short. Most are in the 2-4 weight catagory, but I've seen blanks for sale online that claim to be 5 weight rods. They're all small-stream rods, meant for really small, brushy creeks. That's where such a rod shines. I used to own a neat little 6' 2 weight TFO and it was an amazing small stream rod. I'm pretty sure my next fly rod will be one I build, I'm eyeing up the Batson Enterprises RX6 6'6" 2 weight blank to make into a small stream rod. Sometimes 8' is just too dern long. A 5' or 5'6" small stream fly rod, in 1-3 weight would be about perfect for some of the little creeks I fish.
Now, I will admit that I've played with a Luhr-Jenson ultra light spin rod I own, with a fly reel mounted to it. It's a 6' ultra light 2 piece, with a straight all cork grip, and two sliding bands for the reel seat. This lets you put the reel anywhere on the cork you want. a 5 weight line really over-loaded this rod, but a 2 or 3 weight would probably work really well. I also admit that sometimes I've fought off the urge to cut the spinning guides from the blank, and tie on new snake guides and a smaller stripping guide.