http://www.theihs.org/libertyguide/ This is a great site that "encourages the free exchange of ideas in pursuit of a better understanding of the foundations of a peaceful, prosperous, and free society."
If you want to become more active here is their list of resources -- very cool links. http://www.theihs.org/libertyguide/links/index.php
Online Libertarian Meetup Sites are a great resource for helping interested people get information on their area's Libertarian happenings. The link I visit most is http://libertarian.meetup.com/217/ or check out www.meetup.org
I posted these links under "Local Level" as well, because it will assist people locally, but also is great for an overview of the Libertarian Movement on a national level.
Thank you jet! If there is anyone else here who has resources to list, please do!
Just came across this resource site that includes discussion lists, announcements, directories and more: http://www.libertarians.net/
Looks fairly inclusive.
"The Hand the Rocks the Cradle is the Hand that Rules the World" ~ William Ross Wallace