It's time for text editors to kick it old-school, before graphical user interfaces were the bomb, as Vim is now on iOS. This is not a text editor for the newbie user. In fact, this probably isn't meant for anyone who isn't comfortable with mucking around in command line interfaces. Vim is what is described as a modal editor, where there are different modes to operate in; text can either be entered directly in Insert mode, or commands can be entered in Normal mode. Do not try to jump into Vim without reading about what it is and how to use it. Here's a newbie guide to get started.
Vim can be used for purposes such as typing in code, and text can be highlighted in different colors. As well, by typing in the :new command into Vim for iOS (which is a universal app), two files can be edited simultaneously. Files can be exported and shared through iTunes file sharing. Note that some changes needed to be made to Vim's interface in order for it to work on iOS: in particular, the escape key is now mapped to backspace. Otherwise, typing in ":help ios" in Vim will pull up iOS-specific help.
Vim is an important part of computing history: this is based on the Unix vi text editor, and is a piece of free, open source software available on any platform that it is ported to. It is the text editor used in Terminal on Mac OS X, so it is software that is continuously used to this day.
Vim for iOS has been released by Applidium, who previously released a port of VLC for iOS in 2010. That was pulled in January 2011 due to issues with DRM on App Store downloads violating the GNU Public License - or at least according to Remi Denis-Courmont who complained to Apple about getting it removed. Vim is released under a license that is compatible with the GPL, but under its own license entirely. In this case, Applidium may know what they're doing in order to make sure that free software crusaders can't try to spread the message of free software by having it pulled. Still, interested parties might want to download this one while it's still available.