there are plenty more. Mostly z97 and z170. MSI especially has a ton of moderately priced models with 7 pci-e slots. Asus has a few but are a bit more expensive. I have yet to see a 7 slot offering from either asrock or gigabyte.
even though the boards are ~40-50$ more at the cheapest, wouldn't this save money vs buying a new cpu/ram/psu for another setup by being able to squeeze another gpu/dual gpu into the 7th slot? Also all of these boards would be easier to resale than one-trick-ponies like the h81 pro btc boards.
Just curious if anyone has any input because I'm days away from ordering my next rig! I've helped in this community a bunch and appreciate what you guys have to say.