My mother pays something like $50 a year for online greeting cards. Do the quick extrapolation on how many mothers there are in America, how many of them use the Internet, and how many you can reasonably convert. Yeah, $40 million for a market leader doesn't seem that unreasonable now does it.
You will not get invited to give conferences at The Future Of Web 3.0 2012 if you make greeting cards. Nobody will ask you for your insights on scaling, principally because at your scale it will be a boring engineering problem with well-understood solutions. You'll just put smiles on a few mothers' faces and, oh, well, there might be a little bit of money involved.
I think I've mentioned this a few times, but to say it one more time: grown women have money, too, and nobody in tech wants it. Instead of building stuff they want and charging money for it (money they have and spend), we want to push CPM levels to about a quarter (trending towards dimes!) while making social networks for the same people who are already members of six.
There sure are a lot of folks helping startups. I've got a stack of books on startups, e-commerce, and innovation. Hopefully you can distinguish yourself from the rest of the pack. Best of luck. Look forward to hearing more from you.