I think it absolutely makes sense to embed as many slaves into konqueror as possible (like your example of Napster). IO-slaves have two big advantages that come to my mind: fist, if the core of kde gets an update every "protocol" or "application" who uses IO-slaves is automatically updated and second: after all, the information which is being accessed to through IO-slaves is very "database-like". That means that it's sortable and everything is an object (=a file), whether it's an LDAP entry or a MP3-file on your Rio. The user benefits from a _single_ user interface and he can use sort functions of konqueror or link or drag'n'drop or whatever cool stuff konqueror does, too!

Instead of reinventing the wheel and create own GUIs for applications like Napster or Diamond RIO (which deal with about the same objects, more or less) why not use a very functional and stable base? It's like with templates in your word processor: you wouldn't write your company's address onto every letter you write. Instead, you create _one_ "base" (= the template") and with every new letter you automatically get the newest header / footer.

All in all: very cool stuff. I've been waiting for this kind of thing for a long time!