Well, yes and no, and not really...

I mean that yes, you could do it, provided your users are given an rss module that allows them to it up, with admin privs for it.  But, no I don't think that's what you really want.  Since, you don't really describe the scenario that you envision, I'll put one out here:  offer a list of avaialble news feeds in some type of drop-down selection, and allow users to pick, and then save their personal choices.

And that's where the not really comes in.  There is nothing in the standard module that would allow this type of thing.  Not sure I'd want to provide it for users, anyway, as this feature is already present in the 2 top browsers, IE, and Firefox.  It would be a lot of code development to do it, and a lot of trouble to keep up with the fast changes in formats of the individual feeds, as you also have to provide a standard transformation routine or individualize the xsl's for each feed.

Of course, all of it, is just a challenge, and obstacle to overcome for most hardcore developers, but it's probably not going to be free, because it is a lot of work.  Just my opinion, and further discussion is always welcome.