A question with absolutely no relevance to myself:

How would a programmer with a stellar SO reputation (like 30k+) market his or herself to poential employers/investors who have never heard of SO?
In other words, how can one describe SO in a few sentences that will make a high reputation sound impressive at an interview?

In an interview, you wait for the right question. Something about "how do you keep current with technology today", or possibly "would you describe yourself as active in the developer community" (a question you are much more likely to be asked if it says "active in the developer community" on your resume) and then you say something about SO and how it's "a question and answer site where other users award you reputation points for good answers and good questions" and then give your score in really round numbers and then translate into English like "which puts me in the top 1% of users on the site. I'm happy to be recognized as helpful in the technologies I use a lot."

On your resume, you could simply include your SO handle in the contact section, along with your Twitter handle and link to your blog, assuming they're technically relevant. People who recognize it will go check your rep. People who've never heard of it won't learn anything from a simple sentence on the resume.
