I just answered this question for someone on Linked In and thought it would make a good blog post

Question:

Is there an SEO advantage to having multiple domain names pointing to the same sight? (sic)

Answer:

Google will penalize you if you have duplicate content under two or more domain names, but if you have a domain you use for a print or tv campaign, and use Google Analytics or another web analytics program, you can set up to following situation to track the campaign.

www.2nddomainname.com points to a page that forwards to the following link : www.primarydomainname.com/landing_page/?campaign_code  This can be done with a meta refresh, javascript, or apache header, depending on the server technology you are using.

Use the Google URL Builder to create a URL that will work with Google Analytics.

Another thing to remember is the www.primarydomain.com and primarydomain.com are different domains in the eyes of Google, so make sure you pick one and stick with it for all your linking, SEO, and other online marketing.  You can also set the primary domain in Google Webmasters tools.

SEO is more than just domain name, so make sure the content of the site is strong and there are lots of high quality incoming links.  Google Webmasters tools are a free way to get some good insight in to your domain.  There are better tools out there, but Google Webmaster tools is a good first start.

After a couple of months of putting it off, I just completed the exam for the Google Advertising Professionals certification.  The online exam was pretty comprehensive and covered some topics I had not anticipated. Most of the questions were about the mechanics of managing accounts, optimizing advertising budgets, choosing keywords and developing a marketing strategy.

In addition to this snazy logo and a link to a page verifying my status, I get access to promotional credits for new clients.  Credits may be applied to a new client account (no more than two weeks old) that I manage. Each $100 credit is good for 1-to-1 dollars worth of free AdWords advertising.

If you are on the fence about Google Adwords advertising, or just want to learn more, you should read the following overview document.  How to get the most out of your ad budget (PDF 944 KB)

Feel free to contact me via email or phone for more information about using a promotional credit or for help managing your online advertising.

Also, if you have not checked out my upcoming free class on search engine optimization and adwords, you really should attend.  It is a short, informative class, that will help you make smart online marketing decisions.