I couldn't find if this had actually been submitted as an idea, so I did so. If you're reading this thread, then it's probably worth the 10 seconds to click over and vote for it: Calculated Metrics in Cohort Tables in Analysis Workspace (I'm assuming the moderator will approve the idea fairly quickl...

As noted in this forum thread: Calculated Metrics for Cohort Analysis The specific use case I had was that I wanted to do a cohort analysis based on visitors that had viewed a specific piece of content. Ideally:A segment for visits that viewed that contentThat segment used in a calculated metric -- ...