My Big Question is.... Can a home page act as a high-converting landing page that promotes a site's main product (in this case, an e-book) and complements an Adwords campaign for that product as well?
This is just a general observation about landing page conversion. To score well with Google on Quality Score you need a page that (in Google's opinion) gives 'good user experience'. This means relevance to the ad (which I agree) & lots of relevant information. On this second point - I don't always agree.
If you are trying to sell your e-book off the page you do need lots of info. However, if you want to give away some free info in return for your visitors e-mail info - you want to provide less info & focus your site & visitor on the email application form.
I have found on my sites that less info = more emails. I don't know about you but I definitely complete more 'free info applications' if the site just gives me the main bullet points above the fold & has a well designed clearly visible app form.
The problem is less info = more email apps, can = lower QS with Google & higher CPP.
What bugs me about Google is they don't practise what they preach. Look at Google's home (landing) page. It could'nt be more basic. There is NO 'good user experience' here by their definition. No news, no pictures, no ads, in fact just about NOTHING other than the 'search' bar. Why? Because Google don't want you to be distracted from making your search - & they know more info on the page might distract you!!!!!
Your quesrtion : "Can a home page act as a high-converting landing page that promotes a site's main product (in this case, an e-book) and complements an Adwords campaign for that product as well?"
The answer is yes. What you need to do is write a compelling piece of copy and have this on your main site.
Now break this copy into two parts. Let the headline and opening paragraph be in a separate file from the rest of the copy. To do this --- you would need to know how to do server side includes on your page. If you have a web hosting company that offers PHP (most do), this is easy.
See the POST below this POST...where I've included a quick tutorial on working with PHP Includes.
-----How to Use PHP-----
Almost all webservers now use PHP. If your host does not allow PHP - change hosts immediately. Many of the software products we recommend in this book also run on PHP.
In your case, you only need to know ONE PHP command. It's called the include function.
To make your site flexible you would need to keep the header and footer in a single file separate from the rest of your pages that contain copy and content.
You then include these into your page using the PHP notation
<? include 'filename.php'; ?>
(PHP statements are always enclosed in <? and ?>.)
So rather than your pages looking like this:
<html>
<body>
<!-- MENU GOES HERE -->
<p>Home | About Us | Contact Us</p>
<!-- BODY GOES HERE -->
<p>This is my body copy</p>
<!-- FOOTER GOES HERE -->
<p>Copyright 2006 MyCompany.com</p>
</body>
</html>
Your Page would instead look like this:
<? include 'header.php'; ?>
<!-- BODY GOES HERE -->
<p>This is my body copy</p>
<? include 'footer.php'; ?>
The header and footer are now in separate files called header.php and footer.php respectively. You only need to make one change to the master header or footer file to see the change propagate over all your other pages.
But wait - there's one more thing to remember. Pages that use PHP must end with .php rather than .html. So, for example, rename your page name from index.html to index.php.
Now that you have your site set up this way...simply point your Google Adwords campaigns to different variations of your page where everything except the headline is different. For example, ads targeted to "TALKING TO CATS" would send the user to
www.yoursite.com/landing_cats.php , while ads targted to "TALKING TO DOGS" would send the user to
www.yoursite.com/landing_dogs.php.
The only difference between the two pages is that the file which contains the headline and opening paragraph are customized to the ad audience. Cat or Dog owners. One headline could be "How to Talk to Dogs" while the other could be "How to Communicate with Your Cat". The opening paragraphs could also be customized.
After grabbing the visitors attention with this targeted headline and opening. You can then lead into the rest of your copy.
You can see examples here on goldmanmethod.com
A regular visitor sees: http://goldmanmethod.com/
A visitor from google ads on "Improving Quality of Life" sees: http://www.goldmanmethod.com/index_lpo.php?prid=3532
A visitor from ads on "Relationships" sees: http://www.goldmanmethod.com/index_lpo.php?prid=3560
As you can notice...just the top section (header and intro paragraph) change to suit the ad. Ourt test showed a 30 - 50% boost in signups using this method.