My tiny 8 year old curses-based application Bibcursed has some reasonably dedicated users. One of them sent me a bug report recently, so I've just put together the first new release for five years or so. You can grab it from SourceForge.
I think I'll Mac-ize it next... put a GUI on there and see what happens, although I'll keep the curses version too. Terminal-based apps are usually all you need for useful tasks, and the ability to run them over SSH in a terminal is useful. It sounds daft, but one thing that attracted me to OSX is the fact that BASH and vi and there by default. Windows just doesn't have that functionality and probably never will, which is why it will never displace UNIX when it comes to serious usage in critical applications.