I need to create some email templates but I am not familiar enough with HTML to create them on my own. Rather than contracting with a graphic designer, I am hoping there are companies that provide drop and drag email template builder tools online. If anyone is aware of companies that provide services like this, please let me know.
Also see the new LP creator tool and templates.marketo.com.
If you want to go beyond what Knak does, you'll need to hire a professional.
I second knak.io - I took a look at it last week and it looks pretty cool. A word of caution - if you do contract a developer to code a template for you, make sure they know how to code for Marketo, and not only for emails. That will save you a lot of time and money.
A third vote for trying Knak. Very easy to set up and use. We've tried to go the freelancer route for templates in the past, and it ended up being expensive and a major headache--lots of lost time trying to educate the freelancer on Marketo and squashing bugs.
Just as an aside, I would highly recommend picking up as much HTML knowledge as you can stand. You may not need or want to become an expert, but I believe having some functional knowledge of how an email is structured would be invaluable.