I just came across . I'm sure there are many similar services available out there but I doubt many of them are better. It very simply allows you manipulate and join various data of your choice from around the web, combining them or "piping" them into a mash-up feed of your own. This is fantastic. It takes a lot of the stress out of handling multiple feeds on your own development end.
The interface is simple and easy to understand as you can see above. I think it's a great way of representing and collaborating useful data. I created a simple security feed for myself to be used by an IRC bot and fed into a relative channel. I also plan on using this to mold various news sources into a separate daily news feed for myself!
The beauty of it also, is allowing your feeds be represented in various forms such as json. I'm surprised I never came across it before! Nice one Yahoo!