Other than typos, 301s for previous links or type-in traffic we have only used a supporting domain for advertisement/other marketing purposes that is catchier than the company name and main URL. This domain just 301s to the main domain.

Something like this can be used in print ads, commercials or billboards to get an idea of the traffic resulting from and subsequent effectiveness of the ad. A similar idea is setup with particular landing pages like www.godaddy.com/superbowl.

Using a different domain for this would not create the best brand recognition for the main URL, however. In our case, it's beneficial to use since the URL is the main slogan of the company as well.

To piggyback on what scodtt wrote:

If we send out a mail campaign and plan on putting the same content in a blog post, then we change the link found in the header of the email to go to the blog post and not the page they create:

Email not displaying correctly?
View it in your browser.

Hit Edit on that portion then edit the link to go to your blog post.

check the image for visuals

eN4RbS4.png

For those that are interested, we figured out the root of the problem and the fix. Maybe this will help someone down the road. Thanks to all that responded.
As it seems all the domains/accounts hosted on our VPS are top level; so we couldn’t use robots.txt to fix this.

The problem:

-We have a handful of websites using a shared IP address – Only sites with SSL cert get a dedicated IP
-Some of these websites have additional A record DNS names (mail.domain1, ns5.domain2, etc) that all resolve to that shared IP address
-Within your browser if you went to one of those records it would pull up the website (account) that is first alphabetically within that shared IP pool
-It’s assumed that a website or multiple websites somewhere in the web must have linked these domain names somewhere on their webpages – so search engines crawled them for the content of that first alphabetical website
-Search engines then indexed the content of that site for these other DNS A records and displayed the alternate URLs in the SERPS

The fix:

Edit Apache’s httpd.conf file on our VPS – adding a new (first listed) virtual directory of that shared IP address to point to the servers cpanel default cgi page instead of listing one of our hosted accounts first.

This page describes what we needed done and what fixed it for us: http://forums.spry.com/cpanel-whm/1568-how-can-i-change-default-page-ip-address-points.html

Thanks again!