How to list the Facebook groups available?
My groups page lists groups where I'm a member and the button to create a new group but no option to list other groups.
I can search for groups but I can find how to list them, by category, if possible.
It looks like this is currently somewhat broken.
If you go to an existing group (Aleph-One Strong for the Generalized Continuum Hypothesis!), then click on the category in the information, it takes you to a link which appears to be a search link (Outlandish Statements from the above group), but it gives you the message "Please enter a query." If you then put in a search term, it searches among all groups.
However, if you add &q=searchterm
to the link, you get a search for your searchterm in your category. Taking the example from above, http://www.facebook.com/search.php?sfxp=1&c1=10&c2=141&type=groups&q=answer will get you a list of all groups in the category "Outlandish Statements".
With the millions of groups, and small number of categories for groups, a list of all groups in a category would be too large to look through them.
There is no such public directory listing all the open groups.
You will instead have to either
Search for a topic from the search bar and narrow down to Groups, or
See what groups Facebook thinks you will want to join (based on your interests, likes and other data) from Browse Groups.
You can just access http://www.facebook.com/directory/ to browse for users, groups and so on.
Edit: not working anymore.