HTTP with XML specifics

For example, after the creation of some simple, standardized "file listing" XML format, one could tell the remote server "I know text/xml-filelist", and instead of returning some html listing of the files in a directory, it would return the listing in this special format, so that the browser or whatever can display it in a nice column view and you can sort it and select the files just like local folders. you'd also get index.xml, instead of index.html, etc. Someday, this sort of thing should be the default, but, until then...