I am doing my own certicates. I am basically doing my own everything. 😛
Mostly because I want to be able to think about how things aught to work rather than how they do. I want my certs to map 1-1 with application scopes. Why? Because I don't want crappy applications anywhere near keys I didn't give them access to. Also you almost never want to use you master Identity key. Every time you unlock it is a chance for compromise. We can't expect grandmother to know good key hygiene