Conventional wisdom says that after sometime in the mid-80s, the command line went the way of the dinosaur. That may be true for normal users, but text-only applications are still going strong today.
Why bother with programs that don’t have graphics? Lots of servers run “headless,” without a monitor attached to them, so graphical applications are simply overkill. If you’re a Web developer or system administrator, you’ll probably be logged into your server via SSH. You need something that’ll work in text mode.
Most of these applications are open source projects, since big software companies don’t seem to really see a market for text software.
Emacs
This is the ultimate text editor. You can do just about anything in Emacs, from updating your calendar, to tracking your projects, to programming in Lisp, checking your email, and even text editing. It was invented by the ever-controversial Richard Stallman and is the crown jewel of his GNU project to develop a free (“as in speech, not as in beer,” as he says) operating system.
Vim
Vim is a modern version of Vi, the classic Unix text editor. Like Emacs, it has a lot of features with the potential for more via add-ons. People who find Emacs too heavyweight tend to like this editor more. It generally feels lighter, but some people find the modal interface difficult to get used to. It works differently when you’re in “command” mode than in “insert mode.”
Alpine
Alpine is a descendant of the classic text-based Pine e-mail program developed by the University of Washington. It’s very simple to use for people who have basic emails, but experts can tweak it as well.
Irssi
Irssi is a powerful, highly tweakable IRC client. In addition to being a great IRC client on its own, if you know Perl you can use it to run scripts to do interesting things. If you run this on a shell account that uses GNU Screen you can detach it and leave it running without logging out of your favorite IRC channels.
Lynx
Lynx is a Web browser that’s been around forever. But what good is a Web browser that doesn’t show graphics? People who have vision problems often use screen readers and Lynx gets along just fine with them. If you’re a Web developer, it’s an eye-opening experience to test your pages with it. You’ll see immediately why it’s better to focus on content rather than how it looks.
NetHack
All work and no play makes Jack a dull command-line jockey. NetHack is based on Rogue, an early RPG game. Don’t let the lack of graphics fool you. NetHack is a very deep game. You’ll spend years trying to get the Amulet of Yendor.
For more applications on the other end of the spectrum (with pretty graphics) check out 14 iPhone & iPod Applications for Music Lovers. Since most of these programs runs on Linux and are sparing of the computer’s resources, see also Use that Old Computer with Linux.