The ever insightful jwz posted this old classic involving our own Nat (er, gnat, er):
The article details a conversation where jwz introduced, ad hoc, a new metric. Nearly anything written for the Internet is social software (what isn't is webmaster toolage which helps them build social software).
<<So I said, narrow the focus. Your "use case" should be, there's a 22 year old college student living in the dorms. How will this software get him laid?>>
This rings true. craigslist gets lots of people laid. eBay outfits people in swanky retro hip Adidas gear... and gets them laid. Amazon takes care of that all important gift giving for you... getting you laid, and keeping you laid. MySpace... well, I won't even go there. Suffice to say that kids are doing it too.
Maybe I'm dumbstruck, but I can't think of a more relavent or useful metric...
I write this as a form of note-taking, hoping I'll keep this in mind during the course of my Web ventures.