Since three years it is possible in germany to make one's tax return online without having to print anything or even running to the post office. It's not a web interface, but a special program, called Elster Formular:

Elster Homepage

One of the main problems with this solution is, that there is no Linux version of this program - it is completely tailored for Windoze users. (More severe is, that it is no free solution, but well... let's start small.. ;) ).
Lately I experimented with Wine again, mainly because I needed to use Flash for a university project. Because I heard a lot about WineTools, I also installed them and was amazed. Install of core Windows components was no hassle (I now have IE running here for cross testing web-site designs.. yes, it sadly is a core component ;) ). Perhaps even a little more interesting was the choice to install some mysterious DCOM on which Elster Formular relies and therefore refused to install on Wine in my first try. Looking some further I even found Elster Formular in the list of supported programs!

Well, now today I again had to do my monthly tax return and went to try it out with Wine. Doh, WineTools installed last years version - ok, get the latest from the Elster webpage - install - no problem!! :)
Then doing the tax computation. I had some flickering, but I have that with IE, too. I guess, it's because of my graphics driver - my bro has no problems with flickering in IE. Apart from that everything went smooth as a baby's butt. Great! :)

Don't get me wrong - we need a native Linux solution and we need a free solution - but this is great news never the less! :)