Suggestion: Not all images resize very well. The tooth did better than the gold element. I can really see the halo around the gold piece. The curves are pixilated and not that smooth. When you resize, make sure you use an image format that you can more easily resize, like BMP. A BMP will keep all the data in the image, so it will look better when you make it smaller. Once the image is the correct size, you can export it to a Web-friendly format like GIF or JPEG. If it looks bad in GIF, then try it as a JPEG. JPEG is called a lossy format because the higher the compression rate, the more data you lose and the smaller the file becomes. Try a compression rate of 50% to get a tiny file that will load quickly on your visitors' machines.
Concern #3: I like the light blue background, but you placed red text on it. Those two colors are close to polar opposites. Because of the difference, the colors tend to moiri. In layman's terms, they look like they're moving around. Ditto the dark blue background. It's not a good color choice because you needed to go with white text to make it all show up.
Suggestion: Stick with traditional black text on the light blue background. Find a better color than the dark blue. Choose one that will display black text well. Another light blue block wouldn't be a bad choice.
Suggestion: Pick a smoother font for the larger text.
Concern #5: I looked at your three examples. On your home page you state that the buyer will receive a customized design. I didn't see that. All three of your examples had the same background, the same side stripe, the same red navigation bars, and the same navigation. Basically, you put new information into a template.
Suggestion: Don't get me wrong: I don't see anything wrong with that. It's just that that is not what you are selling. You say you will do a customized design and you don't-- you put new information into a template. I didn't get how it would be possible to for you to design a different site for every new client for $15 bucks a month anyway. Make a point of letting the client know that he or she is not getting a truly customized site. He or she is getting a template. I would offer customized design, but I would ask more money for it.
Overall: I'm really impressed that someone came up with this idea, and furthermore that people are coming to use it. It really shows off the Web at its finest. This kind of business couldn't exist if office rent had to be paid, but it can exist on the Web. How cool is that? Good luck, Joe! I hope every dentist in the world shows up and makes you a very rich man.
That's that. Look ma! No cavities.
Joe Burns, Ph.D.
Always Remember: When it comes to designing your Web site, the most important person is not you but your user.