Vim is an enhanced version of the ever popular command line text editor vi. If you master the use of Vim text editor, it can be a very powerful tool in your hands, and allow you to do amazing text editing feats with just a few taps on your keyboard.
In 2007, this site had conducted a poll, and over 50% of the respondents said their favorite text editor is Vi.
Did you know that a project called Cream of Vim allows you to use Vim just like your regular text editor without learning the Vi commands ?
And if you are an Emacs fan, let me assure you, Vi beats Emacs hands down. :-)
Moving on ...
Henrik Huttunen has created an online site called Open Vim, that teaches a Vi beginner how to use this seemingly arcane albeit very powerful text editor.
Open Vim supports most of the basic Vi commands, and then a few more. It is not exactly a complete Vi editor yet however, the author of "OpenVim.com" claims it is still a functional clone of Vim that can aid Vi beginners to master the rudimentary skills in using Vi.
The main advantage for anyone from this project, as I see it is you need not have access to Vi text editor to master vi. You just need access to a web browser and an internet connection and - voila! you are up and running on the path to mastering Vi.