Currently Being ModeratedJan 28, 2013 1:53 PM (in response to mabunaya)
No. AppleCare sold after the original purchase of the device you wish covered is, to the best of my knowledge only sold as a physical package with the registration code printed on a card. I know that seems a bit archaic in these days of electronic delivery of just about everything, but that's the way it is right now.
Currently Being ModeratedJan 28, 2013 3:22 PM (in response to mabunaya)
No, you cannot get just the registration key - there were too many illegal dealings with keys being sold dozens of times.
But, you can still buy it online - either from Apple or from a reseller such as Amazon or this one - both offer considerable savings:
I have purchased from them as well as Provantage.com several times.