Check out this post from Lifehacker:
"Want to play with RSS feeds? Try xFruits, where, according to tech
enthusiast Steve Rubel, you can "teach your feeds all kinds of new tricks."
He's not kidding around, either: you can create a PDF file from an RSS feed,
send an OPML to your mobile, aggregate, and lots more. I played with it a
little bit and was suitably impressed by all the options; it looks like
they're even adding the option to create RSS feeds for your desktop files
soon. â_" Wendy BoswellxFruits [via
MicroPersuasion]"
(from: Mash up RSS feeds with
xFruits)
I haven't looked at this yet, but it is quite intriguing.
Oh… Why haven't I looked yet? Well ever since xFruits was mentioned on
LifeHacker, it has been unable to be reached. The server is probably getting
overwhelmed by loving interest like mine.
I say "server" singular? I am just assuming that we are talking about a single
server. But even if that's not the case, the fact that the service is
unavailable right now says something about how hard it is to build a scalable
web service, especially if you are giving it away for free. It is why it's
nice to see Yahoo, Google and Amazon publishing services.