Actually you can build your very own domain-name system by
simply making your own webbrowser (not too hard in Java).
You just have to build the extension into the browser and make
the special extension URLs point to normal urls! (not very hard
either). However this is not very useful, as only you will be using
your browser (But it is quite interesting).
Actually you can build a javascript that does almost the same
thing. The user writes the url in a text field, and are then redirected to a page somewhere (ie the homemade URL
"www.janne.rules" can be made to point to
"www.somehost.com/janne").
This system can actually be used (even if only for fun), I once
made a frame-using version of it, where the text-field was located
in the top frame. If only you could make it integrate with all
browsers in the world....
/Janne