Interesting... I tend to work better late at night too. 11PM to 3AM or thereabouts.
Working at home? Forget it, too many distractions...
I have been known to make use of an MP3 player on occasion. Loaded with what my friends call "cheesy 80s pop" and "poodle rock" -- various power ballads, Status Quo, Whitesnake, Billy Joel ... I've got some modern stuff on there too (Goo Goo Dolls, Lady Antebellum and Little Big Town spring to mind) but most of it is pre-1990. I can't stand classical music, techno, trance or "electronica". Digitally Imported (di.fm) is blocked at the firewall on my say-so