Thank you for your reply,
I can preview tar-archieves in konqueror - even gzipped ones - that is not my problem. What I would like to be able to, is to use gzipped html documents (and pngs, gifs etc.) just as if they were not compressed. So if, for example, some folder contains a index.html.gz file, I would like to click on it and view it, just as if it were a normal index.html file. I don't know, if that is a current feature of konqueror ... (This behavior works for ps.gz files. Maybe I just have to add html.gz as a file-extension to the text/html mime-type... I'll try that.)
Greetings,
Matthias