I'm looking for beans that have undergone interesting fermentation experiments. Any suggestions?

I'm constantly on the search for roasters that are working with producers to do interesting things in the world of coffee, particularly with a focus on the fermentation aspect. Of course, I'm very familiar with the roasters in my area, but I'm looking to widen my net a bit. I've got setups for both pourover and espresso, so suggestions for both are welcome!