I think you need to add more graphics and some more contents because the main page is just too bare. You need a logo too. In terms of functionality I have not registered because it is just not my practice to let a third party service "know" what domains I own or the activities that I will be doing.
Perhaps add a video guide. Some screenshots of how your service works would be helpful. pretty basic design but I agree with the others in that sometimes simple is best.
its pretty easy to find out all domains with same registration info if you odnt use whois guard if your domains are hosted on same ip - easy as well
The site is good and very simple. If possible make it an attractive by putting some content changing color contrast etc.
Add your own logo, and change the background color, and give your visitor simple tutorial how to use your website