1. "GIFT CERTIFICATE TEMPLATES FOR YOUR BUSINESS" is not the best tagline, I think. "Template? What's a template?" Perhaps better is something like "Sell gift certificates for your business". The fact that you're actually selling 'templates' isn't really important to them. What they get is the ability to sell gift certificates.
2. Below the "sign up to the mailing list" on the front page the information is a bit messy, and there may just be too much of it. What's the difference between the "features" and "about product" tabs? (I don't want you to tell me the answer - I'm just saying it's unclear). Perhaps just grab the most important points and say them as clearly as possible, without requiring clicks onto tabs or anything. Things like "add the name of your company" are probably redundant - I would expect that I would be able to add the name of my company at the very least! I would probably just junk a lot of that stuff and fold it all into a "How it works" page. Then on the front page you just have "Start Printing Gift Certificates" [not 'templates'!] or "How it works"
Various other of your pages could do with cleaning up a bit like that, but overall I think the idea's probably a good one.
One final thought though: is there any fraud prevention involved? What's to stop somebody just making a really good colour photocopy of their gift certificate? You don't have any ID numbers or anything on the certificates, do you?