So a while back I introduced the developer section of Cu.be. It basically puts all the coding stuff on a different part of the site as not to confuse new users, and to prevent spam submissions.
It broke a while back, but I needed it for the future link to app submissions so I fixed it.
Anyway, you can mess with themes again.
And for those wondering about the PHP/API section, that was something I was working on forever ago. It makes it so you can login with Cu.be on other sites(that want to use it). Kind of like the login with facebook or google things you find all over the place now.
But I thought about it and realized nobody would actually use it on their sites so I never quite finished it(it's at like 80%). Just so you know what kind of stuff may eventually show up in that section of the dev panel.