I too am in the middle of going through the same process. There are a few problems/concerns to remember.
1.) With most of these options, you will be hosting the RSS feeds yourself (on your hosting service). If you do this, you will need to take care to watch your hosting bandwidth usage. If your have a lot of feeds, and a lot of splogs (spam blogs) get hold of them and start using your feeds as content for their sites (which is really what you are wanting BTW), your bandwidth usage can jump and cause you a problem with your hosting company.
2.) The bad part of the other side is that, like you noted, there is no "automated" way to create these feeds.
A couple things I have found in my search:
IceRocket seems to be the best RSS feed creator/hoster that I can find at the moment. I have an account at HostMyRSS, and that service does not seem to be working any longer. Jon is on to bigger and better things (aka The Best Spinner).
With IceRocket, you have to manually type everything in to create your feed though.
So, you are still left with the two problems - you either have to type everything in or you have to host the RSS feeds yourself.
To solve the IceRocket problem, I am working on a iMacros script that will take a text file and create a feed automatically from that. I will still have to create the text file, but this is much easier than having to type everything in on a web site.
If you are willing to host the feeds yourself, you may want to look at RSS Xploiter (I think it is available here somewhere). It is a Windows program that will automatically create feeds for you and FTP them to your host for you to host yourself. It looks like a pretty slick program.