Smos

I think I found a solution. Around every image in the nivo slider there’s a link to the post. I simply removed that link so you can’t click on the images in the slider.

In the plugin editor, go to the code files of the WP Nivo Slider plugin.
There you have to open the wp-nivo-slider.php file. Look for the opening tag of <div id="slider">.
A couple of lines below that you have the following code:

<?php query_posts( 'cat='.$category.'&posts_per_page=$n_slices' ); if( have_posts() ) : while( have_posts() ) : the_post(); ?>
	<?php if(has_post_thumbnail()) : ?>
	<a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>">
		<?php the_post_thumbnail(); ?>
	</a>
	<?php endif ?>
	<?php endwhile; endif;?>
	<?php wp_reset_query();?>

You have to remove the <a> tag from the code so your link is gone.
Then you should have something like this:

<?php query_posts( 'cat='.$category.'&posts_per_page=$n_slices' ); if( have_posts() ) : while( have_posts() ) : the_post(); ?>
	<?php if(has_post_thumbnail()) : ?>
	<?php the_post_thumbnail(); ?>
	<?php endif ?>
	<?php endwhile; endif;?>
	<?php wp_reset_query();?>

It worked for me, I hope it does for you too.

I also don’t know how to do this and if it can be done, but I’m looking for the same thing. I would like to switch themes based on the country my visitors are from.
If I find something I’ll let you know.