<blockquote> too many words. a good tagline has just a few words that
give the basic idea. what does "building" or "developing"
add to the idea presented in the tagline that is really
critical?
</blockquote>
"Verbs are golden" (American Society of Newspaper Editors, http://www.asne.org/kiosk/editor/98.dec/mcgrath1.htm).
The Nielsen Norman Group tagline, "Strategies to enhance the user experience", is strong in part because it uses a dynamic verb. Incidentally, this tagline has exactly the same number of words as "The Foundation for Developing Online Communities".
However, now that I think about it, "develop" is probably more powerful than "developing" since it's shorter (http://www.cs.columbia.edu/~hgs/etc/writing-bugs.html).
What about, "The foundation to develop online communities"?
I like this tagline because it reads well for techies who are focused on developing the software and non-techies who are focused on developing the community.
