Combine multiple feeds into one with FeedMingle

I normally use Yahoo! Pipes to combine multiple feeds into one, but that's like swatting a fly with a sledgehammer compared to FeedMingle. It's a single-use site that does nothing but combine feeds and spit out the results in RSS, Atom, JSON or HTML widget flavors.

FeedMingle will autodetect feeds if you're lazy like me and just feel like putting in the main URL of a site. It doesn't matter whether you input the Atom or RSS URL anyway, because you have your choice of output formats. The feeds that FeedMingle creates work fine in a few readers I tested, but I'd like to see them distinguish which source feed each item came from.

Tags: atom, feed, feedmingle, JSON, rss