I was reading through the Op. 39 waltzes for four hands piano with my dad (a Brahms scholar) last night and decided to orchestrate at least the first one today in celebration of Brahms's birthday! He's 174 today (what geezer).
If I get my act together, expect at least a few more in the future because I'm completely taken with these and I can't believe Brahms never orchestrated (it's not like Dvorak, you can't orchestrate a single four hands thing he did because he's already been there and done that! But eh, he'd do a better job anyway...).