As per "The 7 Essential Meta Questions of Every Beta":
Imagine you’ve just gotten on an elevator with a friendly stranger. You have precisely one floor to describe your community to them. What would you say? The elevator pitch is a brief sentence that describes what your site is about. Every word counts!
Once decided, it can be sliced and diced to form:
Examples of "pitches", taglines and mottos
The tagline:
< placeholder >The motto:
< placeholder >The blurb under the logo:
< placeholder >A convenience redirect “nickname” for the site:
< placeholder >Perhaps eventually the domain name in some form:
< placeholder >