I played around with Yahoo's pipes
a while ago when it was just released and found the thing to be utterly confusing. I played around with it again today and I must say once you have a clear idea what you want to do it's pretty powerful.
A while ago the creators of the online comic strip Unshelved (it's about libraries, the people that run them, the lunatics that visit them, or was it the other way around?) decided to inject their blogposts into the feed that had previously housed only the comic strip.
Whenever I get to work my first order of business is to start up Firefox and load up Newsgator, which houses my feeds. I subscribe to 5 daily comics: BC, Wizard of Id, Savage Chickens, Unshelved and Dilbert and about 50 more serious feeds, most of them workrelated. I think I have about 100 new items to shift through every morning, and about 50 during the rest of the day, but this is clearly highly dependent on the day. If a feed that is just for amusement starts getting littered it's not really worth my time to stay subscribed. Unfortunately Unshelved is about a library and as I work with librarians all day I didn't want to just unsubscribe because of some cruft.
So! today! I! looked! at! Yahoo! Pipes! again! (sorry, I can't keep this up) and created a pipe that strips the Unshelved feed from all the redundant blogposts
and just leaves the comics. If you have a yahoo account you should be able to see the source of the pipe* or create a variant, others can just subscribe to the RSS feed of the output if they so desire.
*) It's really very very simple.