I do this. I live in the command line exclusively and have for over a decade, except for web browsing (Lynx is extremely useful though) with Firefox + pentadactyl, and PDF/image,video viewing/editing.

But then again I'm a little biased, since I work for a company that makes our own vi, perl, awk port of entire POSIX APIs for Windows and UNIX shells etc. And cross platform ALM suite of applications (Linux, Solaris, AIX, HPUX, Windows, Mac OS X). I can't imagine being a developer and not being in the CLI 99% of the time.