You can do exactly this with segments

Cheers,
Daniel

P.S. Don't forget to review the component here:
http://extensions.joomla.org/extensions/content-sharing/mailing-a-newsletter-bridges/21710

Hey Lennart,
Thanks for the kind words! I hope that you've already filled out the survey:
https://docs.google.com/spreadsheet/viewform?formkey=dE9FVGxJcDVDcDVkcHgtbXhNcTU5bGc6MQ

Back to the lists. What exactly is the problem? And why do you want the people on your website to subscribe to multiple lists?
Why not use advanced segments for a list?
http://kb.mailchimp.com/article/how-can-i-send-to-a-segment-of-my-list
You could for example create a checkbox field in the form with options:
list 1
list 2

the user will select one option when filling out the form. When you send the email over at mailchimp you'll be able to send it only to people that have selected list 1 in that field?

What do you think?
Regards,
Daniel

Thanks for the quick reply. I didn't know advanced segments, thanks for the heads-up.
It's about different content for different people. Some want info about category A, other from B and C and some others about A and C. Multiple lists = users can choose which content they want

Thanks for the support! Great component and great support. Will place a review on JED. Here it is on my testsite: http://staging.bclandegem.be/jupgrade/index.php?option=com_jumi&view=application&fileid=2&Itemid=326

You can maybe make a list of the segments in HTML

what do you mean with "make a list of the segments in HTML"?

Sorry, didn't explain it well. The problem is that all the segments are generated as labels. This makes the view (with the checkboxes) a little bit sloppy.

Instead of <label></label><label></label> ..., maybe something like:
<ul>
<li><label/></li>
...
</ul>

add this to your css file:

.cmc-signup label.checkbox {

display: block;

}

this will show them like a list.
Regards,
Daniel