About a week ago, I wrote:

This post is already longer than I expected, so I'll hold off on posting my personal favorite pipe until tomorrow.

And then proceeded to leave you all hanging. Sorry about that.

Here's the lowdown on the coolest Pipe I've seen for a while now.

As a long-time Flickr user and an avid consumer of RSS feeds (thank you, Bloglines), I've easily had 20-30 Flickr generated RSS feeds in my subscription list. Being able to subscribe to people, groups, searches, and tags makes it easy to track a potentially large pool of photos without a lot of effort.

But there's always been one feature I wanted: the ability to get a feed of my friends' favorite photos. I'm fan of relying on the filtering of others' when it saves me time.

Well I just happened to come across this blog post which mentioned a Pipe called My flickr contacts' faves. Much to my surprise, it's pretty much exactly what I wanted.

Now I can easily see which photos my contacts are marking as favorites.

Check it out!

There's also a related discussion thread here in the Flickr Hacks group.

Oh, and in case it's not obvious, there's another reason I like this Pipe. It's an excellent example of how someone could effectively add a feature to one Yahoo! Product (Flickr) using another (Pipes) without ever having to even ask us for permission.

That's the power of Pipes combined with a good set of RSS feeds or simple APIs.