DISCLAIMER: I am in no way, shape, or form affiliated with LinkAssistant.

Now that that's over with, I will tell you about it.

It allows you to put multiple lists in a table, with checkboxes. A user can subscribe to the newsletters with the click of the button. It'll e-mail each list owner that they subscribed to with each subscriber. I think it'll be good with thank-you pages. I have been searching for this, and I know some of you have probably been too, so here it is:

http://www.listassistant.com