Dear Andy,
Please apply these moves. Remember, there is no one answer, its many, many factos working on a cohesive manner.
You have a challenge, you design for the consumer base, but you need to address SEO + SEM points.
Meta Tags
1) Your title needs to address the appropriate key words you prefer. ( Bad title)
2) Witihin you Meta Tags, your keywords focus more on Mambo, than Joomla. Add more. (No exclamation points)
3) I became your customer from the MamboDev.com days. Please ask your existing customer base to change their footer notes that read
www.mambodev.com (Example:
http://www.centrodeportivo.com ) You will be surprise how this will assist your backlinlk and that new link write: "Jambo Works Joomla Templates"
4) As mentioned above, this is not a template issue. You lack the fundamentals of SEO SEM
5) Place your web site at directory
www.dmoz.org - This should eventually get you into Google's Directory
6) Your Post - Go back to your entries and fill in the descriptions and keywords.
7) REMOVE THIS FROM YOUR Meta and replace <meta name="title" content="Frontpage" />)

Look at your description = use PLURAL TERMS whenever possible
<meta name="description" content="High-quality custom Joomla!/Mambo templates,
the premier Mambo Template Club, training, professional development services and products." />
9) Keywords - From point #2 - Mucho Mambo - *** Nobodys searches Joomla with exclamation point, Remove
"!"<meta name="keywords" content="jamboworks, Joomla!, joomla, mambodev.com, template club, templates, template, mambo templates, custom mambo templates, custom mambo components, custom mambo modules, free mambo templates, mambo demo, templates demo, mambo skins, free download, mambo addons, download templates, portal, forum, weblinks, tips, tricks, help, PHP, MySQL, web development, graphic design, mambo, mambo open source, Mambo, Mambo Open Source, CMS, cms, MOS, mos, downloads, files, templates, news, modules, training, mambo training, joomla training, online training, developer training, user training" />
10) Slash in title does not help us the visitors, not to mention ithas no value from search perspective. OUT.
11) Open the Syndication Module on all pages.
12) Every page should have a different title. Never repeat your title or meta tags.
13) Focus on forum to assist your optimization.
Call me Geoffrey 203-746-7589