I was just browsing the Subtext's Ohloh Metrics Report (previously mentioned here), playing around with some of the cool Contributors Features when I saw something new... a little box that said "0 Stacks, Stack It!"

WTF is that? was my first thought... but before looking into it I clicked "Stack It!" and suddenly Subtext had 1 Stack. My next step was to figure out what I had just done. A quick trip to the Ohloh home page and I found my answer:

New Feature: Stack It!

We've introduced a new community feature called "Stack It!" which allows you to browse the open source software actually used by Ohloh visitors.

Each Ohloh member has a software stack to maintain. You can add any project to your software stack, and visitors to Ohloh will know that you use that software.

We're excited about this feature, and plan to expand it soon. We think it will help you answer some interesting questions:

• Which open source projects are most popular in terms of actual usage?
• What software are other people with similar stacks using?
• By exploring another user's stack, can I discover new software that would be useful to me?

You can get started by clicking the "Stack It!" link on any project page.

Ahh... that's kind of cool. By adding an open source project to my Software Stack I'm saying that it's a piece of software that I use.

Perhaps that doesn't seem all that useful to you (or me) on an individual level, but it will potentially allow Ohloh to extract some interesting metrics about software usage patterns.

For example, it might be interesting to see how different applications tend to be used in conjunction... or at least by the same sets of users. I could envision this leading to some cool mergers/partnerships across the OSS community when Project-A realizes that a majority of their users also use Project-B.

At any rate... it has the potential to provide some pretty cool, interesting, and surprising looks into how software is used in the real world.

So go sign up for an Ohloh account and start building your Stack!