ReflectionMedia

This should do the trick.

<?php
$args = array( 'numberposts' => 1, 'orderby' => 'rand', 'category' =>21 );
$rand_posts = get_posts( $args );
foreach( $rand_posts as $post ) : ?>
<a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
<?php endforeach; ?>

Figured it out eventually. Wrote a blog post about it:
https://www.cozmoslabs.com/2011/04/14/svn-eol-and-the-wordpress-org-repository/

So apparently the www.ads-software.com svn converts my EOL from Windows to Mac and because of that you get “The plugin does not have a valid header.”

Anyone has any ideas on what to do about it?

I think that the function you need is called get_terms()

try replacing the plus sign with a minus ??

yup! there are clearly some pagination issues for this plugin. i’m using the thematic theme.

Yes, I also get this problem.

But if a retry a couple dozen of times, it eventually works, I think maybe some servers are overworked… I dunno…

Gabriel