We use CiviMail for our organization's newsletter. In addition to a signup form, we would like to have a "click to view our latest newsletter" link which shows the most recent newsletter from CiviMail. Is there a way to automatically do this that doesn't involve changing the link manually every time a new newsletter is sent out?
There is CiviCRM extension which seems to do exactly what you need: Public Mailings Archive filterable by date, template, etc. It says is compatible up to Civi 4.5 so you might need to contact the developer or test first if you are using 4.6
As you are on WordPress, check out Christian Wach's plugin, it creates a custom post for each public CiviMail mailing. You could link in your mailing to the custom archive page for that post, alternatively you could modify the archives-pages-template.php to output only the last post (ie last newsletter) if you don't want to expose previous newsletters.
Try out the Content Tokens extension and check if it fulfills your needs.
In conjunction with Christian Wach's plugin mentioned above, you could create your own token, as explain in this great post by Coleman.
Use the same (short) link in the e-mail template - and use a link shortener like bit.ly or goo.gl - and just make sure you have the latest newsletter loaded up at the link - with a short link to your Drupal node, WP site, a shared Google doc, wherever.
For Drupal users a View could do the required, based on Civi Mailing, set to 1, sorted descending, with just the Body HTML field, and pager set to show newer/older.
I attached a file to this blog in case it is useful. You would just need to 'add page display' and set your path.