I like the colors, but I'd like to be able to configure what's colored and, more importantly, what gets bolded. For me, the bold stuff jumps out and can kind of push the non-bold stuff into the background, which makes scanning that stuff a bit harder. (In case you're wondering, I think I'd skip bolding the username and the owner perms.) Also, I think that setuid bits are probably worth bolding, because you probably shouldn't see them very often.
Thanks! Configurable colours are something I'd like to get done, too. About half the work has been done to achieve this -- none of the colours are hard-coded, they're all looked up from a big Colours value that gets passed around internally. This value just needs an interface so it's configurable by the user. I've been meaning to open it up to the community instead of just defining an ad-hoc EXA_COLO[U]RS environment variable, but y'know, time.
I'd settle for a flag that disables the rainbow perms, it seems to be a common gripe. It's nearly a dealbreaker for me. But, that's personal preference - congrats on a great util.
